Cannot Create Partition in Partition Manager Error

Hi Experts!
I need help on how to fix this error I get from partition manager. I don't really know what I'm doing here. Here's the error that I am getting from Partition Manager:

Disk Management
You cannot create a new volume in this unallocated space because the disk already contains the maximum number of partitions.
OK
I have windows 7 Operating System and a 1 TB hard drive. Can someone give me a guide on how to fix this?
