Welcome to the ShareLaTeX knowledge base. A complete list of topics is provided on the left hand-side, but here are a selection of useful articles:
Start with our Learn LaTeX in 30 minutes guide.
For more specific introductions, have a look at:
ShareLaTeX and LaTeX have support for a large selection of languages. These include Arabic, Chinese, French, German, Greek, Italian, Japanese, Korean, Portuguese, Russian, and Spanish.