Overleaf.com is an online LaTeX editor. Students are encouraged to use Overleaf for completion of course assignments. Overleaf also includes a number of introductory articles and guides for getting started in LaTeX.
In particular, you can find an introduction to Beamer here. I also recommend the articles on Biblatex, Inserting Images, and TikZ.
Use Biblatex to format your bibliography. You can find a handy biblatex cheat sheet here.
TeXnique is a LaTeX typesetting game where you can practice typing math equations for speed. Don't worry if you get zero points on your first few tries. Keep practicing. If in doubt, Google! And let us know your high scores.
Detexify can help you to figure out how to make specific symbols. Draw them with your mouse and Detexify will show you how to TeX them.
There is a good list of common LaTeX math symbols on Overleaf.
But if you want ALL the math symbols, look at The Comprehensive LaTeX Symbol List
Good intro to different kinds of arrays: https://golem.ph.utexas.edu/~distler/WebTeX/docs/wtxsec7.html
More information on creating annotated bibliographies in LaTeX: http://www-math.ucdenver.edu/~billups/courses/guides/annotated_bibliography.html