vi   e d i t o r

A nice introduction tutorial in using vi: vi intro -- the cheat sheet method (tip: register for free, then download the PDF).

Two key vi websites are The Vi Lovers Home Page and The VI Pages.

There are many versions of vi: vim (http://www.vim.org) is very popular and has a number of extensions that make vi a lot
nicer.

The vi manual pages in the AIX Documentation Library may also be of help.