I believe if you improve DIY skills step by step, you can do more in very soon. To start get some tools like
A screw driver
10mm, 12mm wrench
and try to do very small job first. Like changing a license plate lamp.
The installation manual of reverse sensor kit must provide all necessary info. (Really the auto electricians too learn by it). First thing is trust yourself & your skills. Start the job in a holiday morning. You can complete the job at most in the evening.
Good luck.