Some starter TeX resources

TeX (and its newer variation LaTeX) is the system that allows you to typeset mathematics. In some sense, TeX is a programming language -- you have to create your file (with text as usual, but all mathematical symbols defined by commands) using some text editor. Then you compile your file, and the result is the pdf file with beautifully typeset mathematical document (for example, homework). So, in principle, you will need to install the TeX compiler on your computer, and use some text editor (some are better suited for TeX than others). However, to start with, it is probably best to use a wonderful new cloud tool for creating LaTeX documents. If you are getting serious about this, and want to install it on your computer, try If you are using linux... then it is harder, but then also you probably can figure out how to do it.
Here are some online manuals and more online tools: Here is a document sample -- the source files (in LaTeX) of the first Math 220 handout: