acting, extras,cattle calls, auditions, making movies

has anyone out there been an extra on a filming of a movie, there are those ads in the paper that say you can get paid to be an extra and i've always been interested in doing that - hoping to make more contacts. the one ad i responded to wanted you to purchase their program, and i did because you could get your money back after a certain amount of time, like 2 weeks or a month, anyway, i ended up canceling, but i was wondering if that was the norm and if anyone out there knew anything about how to get a good agent, i live in a small town in eastern oklahoma and i don't know who to contact to find out how to get started anywhere...when i was in college, i was told by a few people i should really really pursue this line of work, i was even approached once by a traveling troupe to come work with them. i was amazed and now regret not taking them up on it and now i can't remember the name of the troupe to even look them up to see what could happen for me yet. all i remember is that they did travel nation wide and maybe maybe something with trees in the title?? with that last part i'm very unsure...some one please help if you can....i no longer want to miss my calling in life...so many people have told me i already have missed it or that i don't have many more chances left...i must try....help in a small town in eastern oklahoma