There are two books I have read that have given me basic information to understand investing. Not a bunch of "self-help" shit like badkins said to stay away from. Just basic info to get you started like, "what's a mutual fund?" "What are futures and options?", etc. They are both put out by the Wall Street Journal.
The WSJ's Guide to Understanding Money and Investing
The WSJ's Guide to Understanding Personal Finance
If you want mutual funds but want to avoid having to rely on a manager, you could try an Index Fund. Basically it does whatever the stockmarket is doing.
Wouldn't be bad to think about a Roth IRA, too. That's money you can't touch until you're retired, but the earlier you start, the better. You will need more money than you currently have to do the IRA, I think. I'm not sure, but there may be some funds you can open with $500.