It is hard to make a recommendation on what you should do, because we don't know your skill level.
Without being unkind to you, the task is not difficult, but if done incorrectly or without the proper tools and connectors, you can get unreliable results, or even cause damage or blow fuses.
If you DO think you're capable, then you will need a test probe lamp and I would identify and test each wire to determine it's function record the results on paper. Disconnect the battery, cut the wires and make solder connections to your plug. I make a point of not cutting the wires at the same length, so that solder connections are never next to each other. Use heatshrink tubing over the connections, reconnect your battery, test your plug and if all is well, bind the whole set of connections to the existing wiring loom with insulation tape. Use a continuous bind overlapping 50% from one end to the other.
Hope I've explained the procedure adequately.