The first instance of the formula would be in e14, right?
then. With e13 blank, this would be the formula:
=d14+e13. This should display the number in d14.
To propagate the formula down the page:
So. Copy the formula in e14.
Then Ctrl+g (go to).
Type in the cells you want to hold the formula (e15:e100) and enter.
The cells will be selected.
Paste the formula ctrl+v.
that should do it.