hey everybody, i am new to the whole car stereo world. I need some help designing a system for my truck, the truck is a 2007 GMC Sierra 2500HD crew cab

so far i have a pair of Infinity Kappa 60.9c in my front doors and a set of Infinity Kappa 63.9i in my rear doors. and a dvd head unit. thats it, haha

I need to get an amp to power those door speakers as well as a single 12" sub for under the back seat and an amp for that. the box i am looking is from subthump and has 6.5" clearance and 0.95cu ft of air space. any help anyone can give me is much appreciated.