If you want to make a partition you would go into...
I'll start at the beginning. Left click unless I say right click.
Click on start.
Find "My Computer" and right click on that.
When the menu opens up, click on "Manage".
When that opens up, look for "Disk Management" and click on that (left section of window).
On the right section of the window find the drive you want to partition (it will be Disk x, Disk followed by a number). There will be a drive letter, don't do anything on drive C:.
Right click on the part that says "Disk X".
When the menu opens up find and click on "Delete Partition".
Confirm any warning messages,
DO NOT DO THIS ON DRIVE C:.
At this point you should have an area on this drive that says "Unnallocated".
Right on this area.
When the menu opens up click on "New Partition".
When the next window opens up click on "Next".
Below where it says "Select the partition you want to create" select the "Extended" option and click "Next".
Click on "Next" again.
Click on "Finish".
It will now say "Free Space" in this area.
Right on this area that says "Free Space".
When the menu opens up click on "New Logical Drive".
Click on "Next".
"Logical Drive" should be select, everything else should be grayed out.
Click on "Next".
You must choose how much to allocate to each partion, probably divide it in half.
By default it will have the total size of the drive already, you could just split this number in half (your choice).
After choosing the size click on "Next".
Now you can use the default "Drive Letter" that's in the box or assign your choice, as you wish.
Click on "Next".
Now you can make a few choices. I would recommend "Format this partition wth the following settings".
"NTFS"
"Default"
Change "New Volumn" to "Backup 1" or your choice of names.
Put a check mark in the "Perform a quick format" check box and click on "Next"
Click on "Next".
Click on "Finish".
Once it's done do the remaining portion of the drive and that's it.You only need to go back to the part that's relating to the "Free Space" for the second drive.
If your totally confused let me know and I'll do what I can to help.