You will have to have a parent or guardian open an account in trust for you.

Try contacting an investing company like Fidelity or Scottrade and find out what kind of account you need.

(1) Open an account with a stock brokerage company.

(2) Buy stock.

There are lots of good companies out there. Sharebuilder is nice because it doesn't have a minimum account size. Fidelity is good because of all the resources it offers. And there are plenty of others, too.