Access2000question

Hi everyone! I have a question within Access 2000. I’m fairly new at this so this may be an easy one. I have created a table. Within this table I have a field “date” and another field “expires”. What I want to do for the “expires” field, is have access automatically input the date. The date should be 183 days from the “date” field. I have tried lots of things and nothing seems to work for me so any help from anybody would be greatly appreciated! Thanks!!