Or you could just use TextEdit, which is much easier if you're not familiar with the terminal.
TextEdit it in /Applications/TextEdit
However, if you really think you need to do it all on the command line, here's some basic commands:
cd
(change directory. Eg, cd ~/Documents/blahblah)
ls
(list contents of directory)
pico
(or vi)
(these are text editors, and neither are particularly easy to use, if not familiar with command line utilities, eg, pico myfile)