Do i have to go to someone to get a new switch programmed or is there a way i can do it myself...Buick century 3.1 2000

SOURCE: i have a buick century 1997 that needs a new fan

This car should have an electric fan. Maybe you mean a new serpentine belt. Yes you can do it yourself. There is a tensioner that you have to loosen the tension on the belt. The old one will come right off and the new one will go right back on. You will have to loosen the tensioner again to get the new one on. It is a pretty easy job. Make sure you draw a diagram of how the old belt is routed.

SOURCE: I have a 94 Buick century. I need to program this new key fob transmitter for entry

Many full service locksmiths have the equipment to clone your old fob if it is a factory equipment. Otherwise the dealership should be able to get you another but you will probably need your VIN and if you have a spare key you should take it with you to the dealer.