How can i start talking to boys without thinking im a idiot?

First of all quit thinking you're an idiot. That will take away any hesitation. Choose the guys you wants to talk to, I wouldn't suggest talking to EVERY single guy. If you enjoy guitar and you see a guy playing a guitar, start up a conversation about that. If he's reading a book you've read, talk about the book. Conversations will usually lead to other things if you start up on something that isn't so mundane. Trust me, I'd continue the conversation if a girl shared same interests as me ;).