Buy an amp wiring kit. It'll include the power wire, ground wire, remote wire, clamps, connectors, fuse, and probably some speaker wire too. Kits can be as cheap as $40 bucks and are much easier than sourcing the stuff individually. The only thing I would recommend substituting from the kit is the speaker wire for some good Monster cable or something.
Mount the appropriate connectors to all the wires.Your power wire (with a fuse along the line) will run from the positive bettery terminal through the firewall, which already has a capped off hole in it. It will appear at the passenger seat's feet area. From there, you have a couple options. You can pull the centre console out and tuck it underneath there, or you can pull the step at the door off and run it down the side of the car. Then, below the back seat and into the hatch. The RCA's and remote wire will start at your deck, and again you can choose whether to run them down the centre console or along the driver door. Connect the ground wire from the amp to a nearby grounding point. There are many available. Mine is grounded to the top of my rear coilover.
The rest is pretty obvious. Mount your amp and boxes, run the RCA's and remote wire into the amp. then the speaker wire from the amp to the subs.