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
.tex extension will indicate to
various programs that the file contains commands.