1. Linux tutorial http://rute.2038bug.com/index.html.gz
2. vim home page http://www.vim.org/
- Docs http://www.vim.org/docs.php
vim is 'vi improved' and in fact on Linux the vi cmd is normally aliased to vim, so you actually get vim.
You can get the real vi in eg /bin/vi, but I wouldn't bother; vim is better.
vi/vim is a modal editor ie you're either in cmd mode or text edit mode. When in doubt, hit Esc key once (or twice to be sure..) and that'll put you back in cmd mode (default when you open a file).
Use 'i' to start inserting text at current position. (Like *nix cmds, its case sensitive)
In cmd mode, cursors keys should work, in some cases also Page-Up/down will work as well.
vi/vim is a very powerful and quick editor and very lightweight. Just takes a little practice, but you only really need to know a few cmds, especially if you are using a GUI eg from your desktop, as you can do copy/paste from there instead of inside vim.
vi has been the default built-in editor on almost all forms of *nix both commercial (Solaris, HP-UX, AIX), as wel as *BSD ssytems and Linux for many years.
Definitely worth getting to know the basics; a real server is unlikely to have a GUI ...
HTH & Welcome to LQ