Please Folow this Steps:-
1. Go to Start -> Computer then right click on Computer. Click Manage.
2. Click on Disk partition. Your C Drive will be shown as a large drive.
3. We will now partition the C drive. Right click on C: dirve area in
Disk 0 and choose Shrink Volume.
4. Accept all the defaults and hit Shrink Button.
5. Wait a few seconds and a new partition will be visible in Disk 0.
6. Right click on the newly created unassigned partition and assign a
drive letter to it (D:) by choosing the Change Drive Letters and Paths....
7. You will now have a D: drive. You are done.
