be careful when fuddling around in the disk management, meaning, make sure you are manipulating the drive you intend on manipulating.
Having said that, when you look at the disk manager, you'll see:
disk.JPG
Volumes at the top and disk 0,1,2,3,4,5 etc on the bottom. In my screenshot, disk 0 is actually my backup drive and not an operating system drive. Disk 1 is my Raid/OS drive. On that drive I have 3 partitions (1 small partition in the front aka 7 ultimate standard). The two latter partitions are my WIN7 32 and 64 bit partitions. At the back of that drive is UNALLOCATED DISK SPACE.
Simply right click and select "new simple volume" and then decide how big that partition will be during the following prompts.
O.k. so you have a disk# that doesnt have any partitions on it. YOu may have to initially right click the disk# and initialize it. More than likely it will already say "UNNALLOCATED DISK SPACE" in black, just right click there and select new simple volume.
Lemme know if this helps or if I've just missed what your asking for.