How do I get my mom and dad to let me join an all star team?

Okay, last time I did try all stars but I quit because I was embarred to death. I dont know what happen. Don't ask. Anyway, I realy want to know my friends are even willing to do it with me. I think about three or four. All in all, I was so embarrased because I am a walkin disatour when it comes to tumbling. I can do everything else with cheerleading, jumps and all. I am a loud cheerleader and all because I cheered for five years for football. I didn't have a problem then because we didn't really do any tumbling. But anyway how will I get my parents to let me do all star cheering again. I know they think I will just quit again but I wont. I really want to do this so help me any ideas about tumbling will be helpfull to. JUST HELP MOI!