RMZ250 Wont idle/Popping

First off, can someone explain how to adjust the idle? Its a bit confusing, I know it involves the choke lever but i dont know which way is what and also the bike seems to run rough, it doesnt want to idle which may be because the idle is too low but also when riding it always wants to die on me if i let off the gas and dont keep the engine running and seems to pop a good bit. Any ideas?