Microsoft access

Im trying to build a database for an advertising agency but have run up against a problem. Im trying to get a combo box to relate to other pieces of information from the same table. In other words you select ‘1’ in the combo box another box displays the next field for that record eg ‘a’. like selecting a product and it displays the price? Any help much appreciated. If you know for certain it cant be done please tell me thats worth the points if you can suggest an alternative as well!