I live in the usa for 14 years and would like to know how can I obtain a green card?I went to elementry school,middle school and finally graduated from High school.What can I do?

Well. Do you have a visa here? I'm assuming that because you went through all the school, that you have a student visa...

... either that or your parents have some form of a visa...

... either that or you're here illegally.

In either case, you would get them from one of the following venues:

Green Cards - 11 Ways to Get One - Apply Online: Fast, Easy, Economical