How do you program the remote keyless entry for a 2000 pontiac sunfire?

You need a connector for the trunk, in the dash, so you may have the wrong or incompatible relay. Aftermarketers have the correct part, usually with an alarm system, also for remote door locks. It has to be separate, if you tapped into a wire you would be opening the trunk every time you open the doors. Also a unique trick, if & when you have everything working properly. Pulling the main red 50 amp. fuse and reconnecting it in the box behind the battery with everything off will open the trunk and doors, on an aftermarket setup.