I've tried to install Pantheon desktop environment several times. I tried sudo apt-get update and sudo apt-get upgrade, but it's no use. I’m just a very new beginner. This is what I’ve done:

quanglong@ubuntu:~$ sudo add-apt-repository ppa:elementary-os/daily
[sudo] password for quanglong: 
You are about to add the following PPA to your system:
 ATTENTION!
Do NOT install this PPA if you want a tested running system, this PPA contains the newest and most unstable development of elementary, it's useful only if you are a developer and are not afraid to encounter CRITICAL BUGS.
Also this PPA may overwrite already installed packages you don't want it to!
 More info: https://launchpad.net/~elementary-os/+archive/daily
Press [ENTER] to continue or ctrl-c to cancel adding it

gpg: keyring `/tmp/tmpkz5d_z/secring.gpg' created
gpg: keyring `/tmp/tmpkz5d_z/pubring.gpg' created
gpg: requesting key 4E1F8A59 from hkp server keyserver.ubuntu.com
gpg: /tmp/tmpkz5d_z/trustdb.gpg: trustdb created
gpg: key 4E1F8A59: public key "Launchpad PPA for elementary OS team" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
OK
/bin/rm: cannot remove `/run/user/root/gvfs': Is a directory
quanglong@ubuntu:~$ sudo apt-get update
Hit http://ppa.launchpad.net quantal Release.gpg                               
Get:1 http://security.ubuntu.com quantal-security Release.gpg [933 B]          
Hit http://us.archive.ubuntu.com quantal Release.gpg                           
Hit http://ppa.launchpad.net quantal Release.gpg
Get:2 http://security.ubuntu.com quantal-security Release [49.6 kB]
Get:3 http://us.archive.ubuntu.com quantal-updates Release.gpg [933 B]       
Hit http://us.archive.ubuntu.com quantal-backports Release.gpg                 
Hit http://ppa.launchpad.net quantal Release             
Hit http://us.archive.ubuntu.com quantal Release                               
Hit http://ppa.launchpad.net quantal Release                                   
Get:4 http://us.archive.ubuntu.com quantal-updates Release [49.6 kB]           
Hit http://ppa.launchpad.net quantal/main Sources                             
Get:5 http://security.ubuntu.com quantal-security/main Sources [74.3 kB]      
Hit http://ppa.launchpad.net quantal/main amd64 Packages                       
Hit http://ppa.launchpad.net quantal/main i386 Packages                        
Hit http://us.archive.ubuntu.com quantal-backports Release                     
Hit http://us.archive.ubuntu.com quantal/main Sources                          
Hit http://us.archive.ubuntu.com quantal/restricted Sources                    
Hit http://us.archive.ubuntu.com quantal/universe Sources
Hit http://ppa.launchpad.net quantal/main Sources                              
Hit http://us.archive.ubuntu.com quantal/multiverse Sources           
Get:6 http://security.ubuntu.com quantal-security/restricted Sources [1,833 B]
Hit http://us.archive.ubuntu.com quantal/main amd64 Packages                   
Hit http://ppa.launchpad.net quantal/main amd64 Packages              
Hit http://us.archive.ubuntu.com quantal/restricted amd64 Packages
Get:7 http://security.ubuntu.com quantal-security/universe Sources [23.8 kB]
Hit http://ppa.launchpad.net quantal/main i386 Packages                       
Hit http://us.archive.ubuntu.com quantal/universe amd64 Packages              
Hit http://us.archive.ubuntu.com quantal/multiverse amd64 Packages             
Get:8 http://security.ubuntu.com quantal-security/multiverse Sources [1,169 B]
Hit http://us.archive.ubuntu.com quantal/main i386 Packages                    
Hit http://us.archive.ubuntu.com quantal/restricted i386 Packages     
Get:9 http://security.ubuntu.com quantal-security/main amd64 Packages [207 kB]
Hit http://us.archive.ubuntu.com quantal/universe i386 Packages               
Hit http://us.archive.ubuntu.com quantal/multiverse i386 Packages              
Hit http://us.archive.ubuntu.com quantal/main Translation-en                   
Hit http://us.archive.ubuntu.com quantal/multiverse Translation-en             
Hit http://us.archive.ubuntu.com quantal/restricted Translation-en             
Hit http://us.archive.ubuntu.com quantal/universe Translation-en               
Get:10 http://us.archive.ubuntu.com quantal-updates/main Sources [134 kB]      
Get:11 http://security.ubuntu.com quantal-security/restricted amd64 Packages [3,469 B]
Get:12 http://security.ubuntu.com quantal-security/universe amd64 Packages [72.4 kB]
Ign http://ppa.launchpad.net quantal/main Translation-en_US                    
Get:13 http://us.archive.ubuntu.com quantal-updates/restricted Sources [2,564 B]
Ign http://ppa.launchpad.net quantal/main Translation-en                       
Get:14 http://us.archive.ubuntu.com quantal-updates/universe Sources [96.7 kB] 
Ign http://ppa.launchpad.net quantal/main Translation-en_US                    
Get:15 http://security.ubuntu.com quantal-security/multiverse amd64 Packages [1,488 B]
Ign http://ppa.launchpad.net quantal/main Translation-en                       
Get:16 http://security.ubuntu.com quantal-security/main i386 Packages [205 kB] 
Get:17 http://us.archive.ubuntu.com quantal-updates/multiverse Sources [5,269 B]
Get:18 http://us.archive.ubuntu.com quantal-updates/main amd64 Packages [337 kB]
Get:19 http://us.archive.ubuntu.com quantal-updates/restricted amd64 Packages [4,804 B]
Get:20 http://us.archive.ubuntu.com quantal-updates/universe amd64 Packages [218 kB]
Get:21 http://security.ubuntu.com quantal-security/restricted i386 Packages [3,531 B]
Get:22 http://security.ubuntu.com quantal-security/universe i386 Packages [73.0 kB]
Get:23 http://us.archive.ubuntu.com quantal-updates/multiverse amd64 Packages [12.1 kB]
Get:24 http://security.ubuntu.com quantal-security/multiverse i386 Packages [1,726 B]
Hit http://security.ubuntu.com quantal-security/main Translation-en            
Get:25 http://us.archive.ubuntu.com quantal-updates/main i386 Packages [334 kB]
Hit http://security.ubuntu.com quantal-security/multiverse Translation-en      
Hit http://security.ubuntu.com quantal-security/restricted Translation-en      
Hit http://security.ubuntu.com quantal-security/universe Translation-en        
Get:26 http://us.archive.ubuntu.com quantal-updates/restricted i386 Packages [4,841 B]
Get:27 http://us.archive.ubuntu.com quantal-updates/universe i386 Packages [219 kB]
Get:28 http://us.archive.ubuntu.com quantal-updates/multiverse i386 Packages [12.3 kB]
Hit http://us.archive.ubuntu.com quantal-updates/main Translation-en           
Hit http://us.archive.ubuntu.com quantal-updates/multiverse Translation-en     
Hit http://us.archive.ubuntu.com quantal-updates/restricted Translation-en     
Hit http://us.archive.ubuntu.com quantal-updates/universe Translation-en       
Hit http://us.archive.ubuntu.com quantal-backports/main Sources                
Hit http://us.archive.ubuntu.com quantal-backports/restricted Sources          
Ign http://security.ubuntu.com quantal-security/main Translation-en_US         
Hit http://us.archive.ubuntu.com quantal-backports/universe Sources            
Ign http://security.ubuntu.com quantal-security/multiverse Translation-en_US   
Hit http://us.archive.ubuntu.com quantal-backports/multiverse Sources          
Ign http://security.ubuntu.com quantal-security/restricted Translation-en_US   
Hit http://us.archive.ubuntu.com quantal-backports/main amd64 Packages         
Ign http://security.ubuntu.com quantal-security/universe Translation-en_US     
Hit http://us.archive.ubuntu.com quantal-backports/restricted amd64 Packages   
Hit http://us.archive.ubuntu.com quantal-backports/universe amd64 Packages     
Hit http://us.archive.ubuntu.com quantal-backports/multiverse amd64 Packages   
Hit http://us.archive.ubuntu.com quantal-backports/main i386 Packages          
Hit http://us.archive.ubuntu.com quantal-backports/restricted i386 Packages    
Hit http://us.archive.ubuntu.com quantal-backports/universe i386 Packages      
Hit http://us.archive.ubuntu.com quantal-backports/multiverse i386 Packages    
Hit http://us.archive.ubuntu.com quantal-backports/main Translation-en         
Hit http://us.archive.ubuntu.com quantal-backports/multiverse Translation-en   
Hit http://us.archive.ubuntu.com quantal-backports/restricted Translation-en   
Hit http://us.archive.ubuntu.com quantal-backports/universe Translation-en     
Ign http://us.archive.ubuntu.com quantal/main Translation-en_US                
Ign http://us.archive.ubuntu.com quantal/multiverse Translation-en_US
Ign http://us.archive.ubuntu.com quantal/restricted Translation-en_US
Ign http://us.archive.ubuntu.com quantal/universe Translation-en_US
Ign http://us.archive.ubuntu.com quantal-updates/main Translation-en_US
Ign http://us.archive.ubuntu.com quantal-updates/multiverse Translation-en_US
Ign http://us.archive.ubuntu.com quantal-updates/restricted Translation-en_US
Ign http://us.archive.ubuntu.com quantal-updates/universe Translation-en_US
Ign http://us.archive.ubuntu.com quantal-backports/main Translation-en_US
Ign http://us.archive.ubuntu.com quantal-backports/multiverse Translation-en_US
Ign http://us.archive.ubuntu.com quantal-backports/restricted Translation-en_US
Ign http://us.archive.ubuntu.com quantal-backports/universe Translation-en_US
Fetched 2,151 kB in 45s (47.7 kB/s)
Reading package lists... Done
/bin/rm: cannot remove `/run/user/root/gvfs': Is a directory
quanglong@ubuntu:~$ sudo apt-get install elementary-desktop
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package elementary-desktop
/bin/rm: cannot remove `/run/user/root/gvfs': Is a directory
quanglong@ubuntu:~$ 



Question: Is Cyrus the Messiah?
Answer: Take this answer as a complement. As Waggers said, the word being used is  רֹעִי (ro·'i) and it means shepherd. (This is in Isaiah 44:28)

But the Jewish commentary sheds light on this issue, because Rashi comments that shepherd is used as a metaphor for king. 

On Isaiah 45:1, it is said that Cyrus is the anointed:


  This is what the LORD says to his anointed, to Cyrus [...]


The words used are לִמְשִׁיחוֹ לְכוֹרֶשׁ, which according to Strong's concordance is "anointed" or "messiah"; but in general it refers to a consecrated person with a special mission.  In this case it is being said that Cyrus will be an instrument of God to facilitate the return to Zion. 

And again, Rashi's commentary complements it remembering how the word anointed is used as a title:


  Every title of greatness is called anointing. Comp. (Num. 18:8) “To
  you I have given them for greatness (לְמָשְׁחָה).” [greatness=portion (NIV); greatness=by the reason of the anointing (KJV); pro oficio sacerdotali legitima (vulgate)]