Info on Selling a Used Car

[GTL]

Parents want me to sell their used 1999 VW Jetta for them. Has about 130k miles on it. Runs well. From the little research I have done they seem to be going for 4k-6k.

parents are going to give me half of anything over 4k. so i could make a quick grand if everything goes well.

I have never sold a used car before. Whats the best way to go about this?

Should I just put a sign in the window and an add up on cars.com or a similar site?

any information would be appreciated.