can anyone tell me some way usefull to say (idioms) in conversation?
I need to lear english very well for studying and meet new people

Really, the first thing you need to do is make sure your standard English is correct.  While you may get away with "it wasn't correct, but close enough, they understand me" in simple English, you simply cannot make mistakes with idioms. They need to be used perfectly, otherwise you end up changing the meaning or speaking nonsense.

If you're really eager anyway, just search for "common idioms English" and you'll find plenty of information.