Okay, first things first. We assume that you have become friendly with some editor (vi, pico, or ``the editor's choice'': emacs, which has a nice mode) and can actually sit down, login, and open a file and edit it. If not, find a computer TF or friend and get these basic prerequisites under control.
is not a word processor, but a formatter. This means
that you prepare a file containing commands for using
a text editor (which is not part of itself), and then
you use the program to convert this file of commands
into a printed document. Any file you make should
have the extension ``
.tex''. For example, the
chapters of your thesis might be in the files
thesisabs.tex chapter1.tex chapter2.tex
jobltr.tex momltr.tex dadltr.tex
.texextension will indicate to various programs that the file contains commands.