First off, welcome to the hobby. I understand why you want a Mustang, they are gorgeous airplanes with a great history. Unfortunately they are terrible for beginning pilots; both for flying and for building. Even though this particular Mustang is a little friendlier than some of the more scale designs out there, it is still too advanced to start out on.

I would recommend either returning or shelving the Mustang kit and pick up a good RC trainer. In Canada there is an organization called MAAC (http://www.maac.ca/). I'd join and find a local RC club with a flying field. You'll find plenty of people there to help you get started the right way. You can also check out www.gettingairborne.com

I know this may not be the exact sort of answer you were hoping to get but trust me, it will help guarantee success with that P-51 when you are ready for it.