Ok i just read that I need to use a 10-12 AWG to connect to the battery and for grounding, and i think the fuse needs to be 12A (inline w/ 10-12 AWG connection) But i still dont know how to connect it to the battery

also, i read some where that there are three wires, a 12v power wire and a grounding wire and there is also a 5v wire ( i think) but i dont know what the 5v or third wire is for. can someone shed some light on this issue?
Thanks
~Ry.