Hello Joshua!
That's a really neat way to help your son enjoy the movies! RS Props is a great choice for stormtrooper armor, I've got their kit and I love mine. Getting everything together can be tricky, and at first I'm sure it can be a little overwhelming, but the good news is there's a number of online resources out there to help!
If you haven't made your way there yet, the First Imperial Stormtrooper Detachment (FISD) at
www.whitearmor.net/forum is your best resource for all things Stormtrooper. From there, I'd look at the different build threads (I know there's at least a few RS build threads) and there's a few different sections that cover the armor, helmet, legs, etc. There's a number of different ways to assemble armor, so go with what will work best for you and still fall into the 501st standards. Feel free to ask questions, and if you need pictures of how my armor is setup I can probably shoot you specific shots if needed, if the RS guys sent you their strapping setup it should be pretty much the same as how I have mine. Posting a work in progress is always good as other Stormtroopers/501st members can help you out when you have questions and we always like to see folks building their armor!
Good luck!
