How can i talk to girls?

Ok i am 15 years old and i sometimes have trouble talking to girls. when i am in a conversation with a girl i just dont know what to say, i feel like an idiot. can ssomeone please give me some tips on what to say or how to talk to them THANKS!!!!How can i talk to girls?
The main thing is just to be yourself! :) Girls are just as shy talking to boys! Try to find something in common with the girls that you are talking to. Talk about a class that have in common, something funny that happened at school, a movie that you both might like...whatever!:) If you're really shy, you can start up conversations with girls on Facebook and MSN and then maybe the conversation might continue in person at school. The main thing as I said, is to be yourself, laugh, and try not to worry about feeling nervous or like an idiot. The chances are,the girls are just as nervous to talk to you! Good luck! :)