Need help with instructions on how to sell cars in forza motorsport 3 in the auction house?

hi, me and my friend just created a sick design on a car using monster vinyls bought off the storefront. we created a car design using these and now we want to sell it in the auction house to make some dough. when we try to do it, it says we cant because it is " locked ". what does this mean and how can i unlock it so i can sell it?Need help with instructions on how to sell cars in forza motorsport 3 in the auction house?
Anything you buy off the storefront is locked to prevent plagiarism when you sell it. In order to sell it you must have made all the vinyls yourself. Same with the tuning setups. You have to take it off and put the parts on yourself and tune it yourself to be able to sell it.