I want to create a auto populating column in access

I want to create an auto populating date column in access that takes the date from the field to the left of it and subtracts 60 days from it and then fills its field in with that. I know the basics of Access and I’m usually pretty good at going back to my textbook when I need to figure out how to do something I don’t remember off the top of my head but this is one I’m having trouble with. Any help would be much appreciated.