Here's the question you clicked on:
Iamgmg90
List of all LaTex code for mathematical equations
just to get you started , http://en.wikibooks.org/wiki/LaTeX/Mathematics
if your looking for a special symbol http://detexify.kirelabs.org/classify.html
A complete documentation is found at http://mirror.ctan.org/macros/latex/required/amslatex/math/amsldoc.pdf