When that screen comes up (posted above), you would hit "d" to delete your old partition, then confirm it. Next, you would be taken back to that screen again. Hit "c" to create a partition just for windows, then name the size (4000 MB = 4 GB). This would take you back to the same screen AGAIN, where you could make your second partition for your data. When both partitions are created, you would choose which one you would want windows to be installed on. Obviously, choose the 4 GB one.

Hope that helps for next time!