Installing LaTeX
To get started you need a version of LaTeX. The program MikTeX is a version for PC. Download the basic installer here.
I recommend using the editor emacs.
If you're a Mac user then you can use TeXshop which is available here.
If you're a Linux (Redhat/Ubuntu/Debian/...) user then latex is probably on your computer already.
Some LaTeX info and tutorials
Here an introduction to LaTeX, thanks to Bin Zhang of SUNY, Stony Brook.
The Harvard TeX manual also provides a good introduction to TeX and LaTeX. This is useful for looking up commands.
Here's a reference for lots and lots of symbols.
There's nothing like playing around with these things yourself, so here's a sample latex paper (and as a pdf).
More examples: here are example1.tex and example2.tex from the classes.