I thought thats what I was doing...Im following these instructions
"Right-click My Computer icon on your desktop and choose "manage" from the drop down menu. Or you can right click My Computer from your Start Menu can choose manage. This opens your "Computer Management" window.
Under Storage, click Disk Management. It may take a few moments for the information to appear.
Right-click on the drive you are changing (make sure it is the right drive), and choose "Delete Partition".
Click Yes on the prompt. You will get a warning that all data will be lost, so double check and make sure you have selected the correct drive, and be sure you backed it up if you are not working with a brand new external drive!
Next, you will see unallocated space for the drive you are changing in the lower right window. Right-click on unallocated space and a menu of available options will appear.
Choose "New Partition" and the "New Partition Wizard" will appear. Click Next. Then Next again.
Choose partition size, click next.
Leave "Assign the following drive letter" selected and click next.
Under "Format this Partition" choose NTFS. Select Perform a quick format and click Next.
Click Finish. You will see that the drive is formatting and percentage complete. If it is a large drive, it may take a few minutes. If it is a drive that has information on it, plan on an even longer time to finish. Congrats! You are done. Now go fill it up
"
But when I get the the partition size I have no idea what to put???