If you dont have screws the hold the gasket and liner to the door frame, this is an extremely difficult job to do, as you have what they call a foamed-in liner. The Liner is literally glued into place, and the liner secures the gasket. You would have to remove the liner, without cracking it, and re glue it. This is a very difficult job for even an expert refrigerator repair service, let alone someone with no experience.
However, unless you have a rip, tear or other deformation in your gasket, if you are having trouble with your door closing properly, check your lower door hinge, cam riser, and any shims. If there are any problems in this area, the bottom of the door can rub on the inside bottom of the cabinet, evidenced by scratches on the inside unit floor.

how do you repace freezer door gasket. i see no screws that hold gasket to door. does door panel come apart to repace gasket.need to know how to separate inner panelfrom out to repace gasket. thank you