Your BMR is the calories you require to carry out basic body functions and keep your organs going. You then get a daily calorie requirement based on your stats/activity level which is considerably higher. This is the figure you deduct the 500/day cals from to enable you to lose 1lb a week and get your net calorie figure. Mine read something like this:
BMR 1944
DCR 2544
Net Cals 1860
So I am eating just a fraction under my BMR really.
HTH