How Do I File Class-action Suit Against Greyhound For Civil Rights Violations?

Unbelieveable - a Greyhound Security employee violated my civil right of free speech by kicking me off Greyhound's property (and Greyhound refused to issue me a refund) because I politely asked a harmless question to a group of other traveler's waiting for one of their busses. I have witnesses who are willing to testify of my doing absolutely nothing inappropriate. I simply asked a question.If Greyhound can get away with such gestapo-like tactics directed toward me then in all probability have done the same to innumerable other's. Would you people refer me to a professional who can assist me in instigating a class-action suit against Greyhound?Thanks,Brinton McClellan