Amps are easy.. You can either try to mount one under the seats, or mount it in the back somewhere.
All you need is a power wire coming from the positive terminal on your battery (you'll need to install a fuse about 6-12" away from the battery), and rout it back to the power input on your amp.
Create a good ground for it.. Pull up a small portion of carpet that you'll never see, scrape away until it gets to bare metal, then tap into it there.
After that, run an amp lead from the back of your headunit (the blue wire most likely) to the lead on your amp.
If you don't have RCA outputs on your headunit, then you'll need a line-output converter (wire your headunit to this, then plug the rca's into the other side) and route the rca's back to your amp.
After that, just run speaker wire, turn the key forward, and hope nothing blows up. j/k
That's just a very basic overview, but it doesn't get much more difficult than that. If you need any more help with anything just get back to me and I'll go more in depth.