Update 1: I have just learnt from the answers below that it is more correct to say that MathJax is the format for writing maths on the Mathematics Stack Exchange, that it is essentially made from the maths part of LaTeX, and that LaTeX is written in TeX. So that resolves my first query.
I have found one guide: TEX Commands available in MathJax:
which is good, but I have to do a lot of scrolling to find anything!
Are there any more resources out there like this?
Also, any advice on how to write TeX in TeXworks, would be much appreciated. A simply written pdf on the topic would be handy, for example. (I don't seem to be having much luck finding one via google) At present, I seem to be getting nothing but errors!
Update 2: Are there any advantages to using TeX over LaTeX in an editor such as TeXworks (i.e. if say I want to create a pdf document?) I have read that LaTeX is more refined, and produces better quality results?