A few game questions

Alright… I’m making a school project with flash. The kids at school are making small Catapults and I want to make a flash game with a catapult… If you’ve ever played The Spear Toss or the Tire Toss games, thats how I want it to work… I have the catapult built and what not, but I don’t know how to make it launch like those other games. Any help would greatly be apprieciated.