Here's the question you clicked on:
OneMathCat
MathJax uses a TeX/LaTeX syntax, and is designed for doing math-on-the-web... when will we be able to use it for the math questions/answers on this site? Here's documentation (it's a big page): http://www.onemathematicalcat.org/MathJaxDocumentation/TeXSyntax.htm
The funny part is, if you had gone to either of the tutorials you would have seen they are short versions of the page you linked.
So sorry --- I didn't know there were tutorials (and I haven't yet located them). I just came across Open Study yesterday, since I was getting people coming to my site from here. I know how frustrating it is when questions are asked that are thoroughly answered elsewhere. This is a great site, and I think it is a great asset to the mathematical community. Thanks!
The are community made. Look to the left. As for re-asking questions, happens all the time here. But there is a more dynamic nature to the content, so this is to be expected.