Q:

using git rebase -i

so I'm trying to split commits using the instructions in http://www.kernel.org/pub/software/scm/git/docs/git-rebase.html
try searching for "SPLITTING COMMITS"
there it says to "Mark the commit you want to split with the action "edit". " 
how exactly do I do that
when I execute git rebase -i it opens a file
# Commands:
#  p, pick = use commit
#  r, reword = use commit, but edit the commit message
#  e, edit = use commit, but stop for amending
#  s, squash = use commit, but meld into previous commit
#  f, fixup = like "squash", but discard this commit's log message
#  x, exec = run command (the rest of the line) using shell
#
# These lines can be re-ordered; they are executed from top to bottom. 
#
# If you remove a line here THAT COMMIT WILL BE LOST. 
# However, if you remove everything, the rebase will be aborted. 
#
# Note that empty commits are commented out

...

how exactly do I execute those commands from that dialog
EDIT
So I managed to rebase successfully and committed to my local repo...
The problem is, when I try to push I get the error message:
 ! [ rejected]        JJ-4322 -> JJ-4322 (non-fast-forward)
 ! [ rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'url.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart.  Merge the remote changes (e.g. 'git pull')
hint: before pushing again. 
hint: See the 'Note about fast-forwards' in 'git push --help' for details. 

any ideas? 

A:

The 
rebase -i COMMIT

Will present you with a list of commits, you can change the default pick command with any in that list
pick 6d6da13 0000, liquibase, fixing build snafu's

# Rebase c56baf2..6d6da13 onto c56baf2

Becomes
edit 6d6da13 0000, liquibase, fixing build snafu's

# Rebase c56baf2..6d6da13 onto c56baf2

Edit:
Your 2nd question is because you are rewriting history and you have already pushed older versions that now conflict with your current state.  You need to do:
git push --force YOURBRANCH

This will overwrite what is on the remote.