Welcome. I have (semi-recent*) memories of AP Chemistry. Good old Mr. Spicer.
If you're over 18, hop on!
If you're under 18, make sure that your parents are OK with you contributing, and
talk to the constables if you or your parents are uncomfortable with using your real name in the project. And then hop on.
Just create an account on the wiki using your real name, fill out a paragraph about yourself (HS Student, AP Chem, from the US), then see what you can help with in terms of chem articles.
* = has it really been 3 years?