I just got a 1996 Jimmy filled it up and now i smell gas outside the vehicle when it is parked no gas on the ground anywhere what is causing it and how do i fix it

Did you put the gas cap back on?
Any check engine lights?
Open hood and have a look amd sniff around under there.
If you can not spot it or smell itthere then work back to the gas tank with sniffing and looking for wet spot.
Post back what you find.