VLOOKUP for cell display in specific order.

I'm looking for a VBA code that takes a specific set of cells and displays their content in an exact order. Specifically, a fifteen minute "clock" that will display 15:00, then when the macro button is clicked, will display 14:40, then 14:20, etc. In ":20 sec:" increments. I teied vlookup and I can't seem to seolve this problem. Thanks for any help.