Also since soft air (as in clear plastic guns from canadian tire) has nothing to do with airsoft (They don't resemble a firearm at all) I don't see a problem with them being shot in the backyard. As long as the neighbors don't get mad and you wear protective goggles. I'm pretty sure thats why canadian tire sells them...to have fun in your back yard.
Since you already own a clear plastic softair gun I am assuming your partents bought it for you. Your partents would have to purchase all the airsoft guns for you. Just read lots about the sport and don't post up already asked questions and you will do fine.