This might help you out, but a further explanation is needed if it doesn't. This formula will work if you have a list of numbers in A1:A100 (or however far down) and you want a running total next to the numbers in Column B. In B1, you would type =SUM($A$1:$A1). Then, press Enter, and double click on the fill handle (The bottom right hand corner of the cell) which will copy the formula down as far as the range to the left. Using the dollar signs with the references this way means that the SUM will always look to start in row 1 and sum all the numbers from row 1 to the current row if you copy it down.