If you already know how to use a Unix text editor, just use it to create the files as described above. If you have not yet learned a Unix text editor, you can use an editor called Pico as follows. Enter the text shown in the section above, substituting your own login name. Press Y for Yes. Be careful with this.
Every character counts, even the slashes, commas and quotes.
You should test this setup before leaving. Send yourself a message and see if you get your vacation message as a reply. When new email arrives for you, the program that delivers mail will notice that you have a .forward file. Before delivering mail to your inbox, it will check the contents of the .forward file for instructions, where it will see that you want a copy of the message and that you also want to run the vacation program. The vacation program checks to see that the message is to you and then will reply to the sender with a copy to your .vacation.msg file.