Since I just installed mine yesterday, its fresh in my mind
First you have to strip one end of the red power wire and put in the round end and crimp that. Then attach that to the battery. Then secure the fuse holder somewhere in reach in the engine compartment as close to the battery as you can. I put mine above the near where the strut bar would go. Then put the wire through the firewall. I don't know about civics, but my 4th gen accord had a pre-drilled hole there with a little plastic cap. I drilled through the plastic cap and put my wire through there. Next you have to run the power wire through the car. I popped the plastic door sill things off and put it through there and shoved it up under the other plastic until i got to the trunk. then just put the big fork end and attach it to the + power on the amp. Next just run the RCA and remote wire the same way but with the RCA on the other side of the car to prevent interference. Next, I pulled the carpet over in my trunk and found a pre drilled hole and took the paint off around it and screwed in the black wire as a good ground. Cut excess off the ground wire to make it as short as possible. Then all you have to do is do the hook-up on the amp which is a no brainer since most all amps are labeled.
Basically what joyride said but mine is longer
Hope this helps