Buy an amp kit. Red wire goes from the positive on the battery through a hole in the firewall to the + on the amp.
Black "-" on the amp is the black wire, connect it to the amp and find a good bolt or grounding place to ground it in the trunk or hatch.
The "Rem" is the remote wire. Should be blue, goes from the amp to the blue or blue/white in some cases on the back of the radio. So when the radio has power it turns the amp on.
Then run your speaker wires + and - to the sub. Mount/secure and hide the wires and your done. Not too hard.