Help!!! Can anyone help me to participate(talk) in classes?

Americans in general really won't care if you speak well or not. As you can tell, some American natives don't speak well anyway. :-) So as long as people understand you, you're alright. In class (college?) no one will really make fun of you. So take solace in the fact that you won't be humiliated.

Don't worry about not using perfect English, with Ebonics and slang words alot of American born English speaking people don't talk right either, I think its cute to see someone learning the English language talk, and it shows just how intelligent and brave you are coming to a new place learning a new language.

Yeah, if you've ever seen Ali G, he does a character called Borat. What you need to do is embody your foreign self, and take advantage of the opportunity that you have to say anything you want to and get away with it, then if it's not right, just say "I'm not from here!" and throw your hands up and grab your crotch like it's a native custom.

Relax and be spontaneous when you want to say something, say it, don't think about it. After you blurt out the first time, it will be easier the next time. I don't think people are out there to be critical and appreciate your efforts. Just do it!

well ... nervos .. thers the problem ... usualy there are all kinds of methods of releasing u of this stress .. just imagine everyone is whearing underware and just udnerware ... you build your confidence by .. talking to yourself in a mirror and imagening the rest of the classe .. of by .. just imagening yourself outside your head .. speaking :D .. that is a good method