Hi Carole Jacoby
I'm assuming that you have a Whirlpool freezer.
Here is a link that shows how to replace the door gasket (seal). It is the same for a freezer as for a refrigerator
https://www.youtube.com/watch?v=rR7G11n6P3I
Here is a link for the part.
''Not sure which is the correct one for your freezer, as you didn't state the model number. Suggest that you use the search box and put in the exact model number of your freezer. If you get no results from the search, contact the 1-800 at the top of the page and ask.''
http://www.whirlpoolparts.com/Shop-For-Parts/a3w1c21/Freezer-Gasket-Seal-Parts