Newer models now sometimes use a gasket that just fits into a groove around the door, but I'll be covering how to replace the older gaskets that use screws to hold the gasket in.

When you get your new gasket, it's quite likely that it will have been folded in a box for quite some time, and will be slightly out of shape or wrinkled. This is simple to remedy. Most gaskets recommend using hot (not boiling) water to warm the gasket, then leaving the gasket on a flat surface til it cools, but this is not the only method that can be used. You may also use a hair dryer to warm the gasket while it is laying flat (or while it is on the refrigerator after installation), or while you're removing the old gasket, you can put it in your clothes dryer on low heat. Whatever method you choose, make sure the gasket does not get too hot, or it could melt.

To remove the old gasket:

1. Pull gently on the gasket's inside edge and pull it away from the inner door panel. You should be able to see the screws holding either a retainer strip, or the inner door panel.
2. Use a nut driver (usually 1/4") to loosen the screws one after the other. Do not remove the screws completely or it makes your job harder. A few types of gaskets do have the screws through the gasket itself.
3. After the screws are loosened gently pull the old gasket out from behind the retainer strip or from behind the inner door panel, depending on the model.

Depending on how warm you got your gasket to remove the creases and wrinkles, you may want to lay the gasket on a flat surface until it cools.

To install the new gasket:

1. You'll want to start at one corner and work your way around. Start by arranging the gasket as it should be on the door and fit the first corner behind the retainer or panel. Continue fitting the gasket behind until all four corners are in place.
2. Start with the bottom corner of the gasket on the hinge side and fit the gasket securely behind the panel and tighten the screws to hold it in place.
3. Work your way up the hinge side of the door, fitting the gasket securely in place behind the retainer and tightening the screws.
4. When you get to the top go back to the bottom and begin at the corner you started on, working along the bottom edge, doing the same as before. Fit the gasket behind the retainer and tighten the screws.
5. Once you have done the bottom, continue to work your way around the door until you have tightened the last screw.
6. Apply a thin coating of petroleum jelly to the hinge side of the gasket to cut down on friction and to allow a better seal.
7. Check the gasket to see how well it seals and adjust as needed. You may need to take a hair dryer to the gasket after installation to get the best seal possible.