As previously mentioned, if you can, splice your stock harness back in.

From there you can either buy a metra 97-2003 for $20 or so and lose your door chimes (like if you leave your key in, and your time/date) or pay $120+ for the other style harness which retains door chimes.

Also if you want your steering wheel buttons to remain functional, theres another harness for that depending on your head unit.