I need help to solve it please with explanation

Third Loop | Name the cells B3 startCount, c3 currentCount and D3 endcount. Add a button named btn ThirdLoop. The button's caption should be "Third Loop" In the click event handler for this button, do the following: Create a Do Loop that "counts down" in the cell named currentCount from the value in endcount to the value in startCount (whatever these values may be). Count down by five. Make sure that your loop does not go on forever