how do i hook up the battery

Always attach the positive lead first, then the negative. Disconnect the battery by removing the negative lead first. It eliminates the chance of a short circuit from your wrench touching metal.

Thank you. The problem is that there are two red connectors besides the usual positive and negative leads, which also go somewhere. The one on the left must be the ground, because I remember it being attached to the terminal on the left...but the one on the right originates from under the seat, and I don't know what to do with that one.

Try to find the other end. Of each. If you can that will help you determine if it's ground or not, but if somebody used a red cable for a ground, they should not have. Does it have some super high draw device? A glass breaking stereo amp? That big cable that disappears under the seat may be to feed some high~draw device whatever it may be

Thank goodness for pictures... It looks like #8 wire that someone used to hook up an aftermarket stereo amp. You don't have to hook it up at all unless it's feeding power to something you need energized. --- A couple of things about the picture. 1. there is no fuse in sight. Always install a fuse near the source of power. 2. the wire in the hand has black electrical tape near the ring terminal. That's the same thing I would do to mark the negative or ground wire. 3. don't hook it up without knowing where it goes

If you enlarge that picture it look like the side where he is holding the red 6 or 8 gauge cable it looks like bare copper going down, and I do see the black tape, I also would identify it that way if I had no black cable on hand doing the project. This is one of those where I wish I was there at the car.... he REALLY needs to find the other end.....good morning

Hello David - I see in the other question about this wire, that it is in a camper. The wires could be feeding a heater. Don't hook them up until you know where they go - especially with no fuse.