hi,
From where and what do I have to download to my computer in order to use LaTex on the forum?
in order to use it, you don't need to have latex installed to use it here.
when posting, at the right try to locate the symbol $\displaystyle \sum,$ and that will generate a tag.
the only thing you need is to know the codes, which is easy, and you can go here: http://www.mathhelpforum.com/math-he...-tutorial.html