You're going to need the Savage Reverse Kit and an inexpensive Servo - I just installed an Airtronics 94102 .. there is also an inexpensive one from Futaba.

I will also tell you as a newbie to this hobby and having just purchased only my second RC (the Savage), it it taking me far longer to install the reverse then most have indicated. I have a friend that did his in 1 1/2 hours. Its taking me far longer but probably because its the first time I'm taking one apart. The instructions, though doing a good job of showing you most of what you need to disassemble, misses a couple of things that you'll need to take apart to get to some of the screws (shocks mostly).

Everything else you need is in the kits you purchase.