Assuming you are running Windows 7, or later.
Go to Control->Panel->Administrative Tools.
Open "Computer Management".
Expand the "Storage" option in the left column.
Select "Disk Management".
Select the disk you want to work with (C: if you are going to shrink it)
On the right, select "More Actions".
Then select "All tasks" from the pop up menu.
The select "Shrink Volume" and go from there.
Once you have shrunk C:, you should have the option to "Exend Volume" for E:.
I caution you to back up everything before you do this.
