How do I splice 2 ends?

Black is negative and white is positive. Make sure when you splice something that you match the two colors together, red-red, black to black, white to white for example. If there is no color coding than you'll have to just have the wire flat on the floor and follow it all the way from end to end to make sure the same wire is going to be connected to the same end of another wire if joining. The positive side coming from your car power needs to match throughout the light to the end or you'll burn our lights or pop a fuse or something, causing a fire hazard. There's typically a red pair of splicing pliers that make cutting wires and taking the rubber coating off easy but you can use scissors too.