How do I go about mounting my amp to the rear seat? I only have 1 amp to power my 1 sub (Stans stealthbox) Will it need a bracket or some type of support? What size screws and what kind should I use?

if the amp came with screws those should work perfectly.. there is metal under the fabric on the back of the rear seats... just find a suitable place and screw it in.. just be sure to make sure you can get the seat back to sit back the way it was and that the amp has ample clearance... here are some pics of mine... sorry they are so big...

Yeah just mark where the holes will be and drill some holes through the sheet metal that a a little smaller than the screws you have. Then just screw it down.