Thanks for the screen shot. It helps.
I'm seeing you have two separate hard drives ... Disk 0 and Disk 1. Disk 1 is most likely an external hard drive so we can ignore that and just work with Disk 0.
Your Disk 0 now has a partition of 100MB (called system reserved which should not be changed. This partition includes the master boot record which allows you to boot or start your computer. If you change this you probably won't be able to use your computer.)
The next partition is the C: drive which contains your operating system and most likely whatever other programs you have installed.
Then you have a 2GB partition containing HP Tools. (I'm not familiar with HP computers so I'm guessing HP has provided some diagnostic tools or perhaps some automatic updating tools to keep your HP computer up to date. For now, I'd leave that alone also.)
And finally you have a partition of 139.84GB of Unallocated space. It's not showing up anywhere because you haven't told your computer how to use this space. So you'll need to change this from Unallocated space to a Primary partition. Once you do that you should see it in the upper panel of Disk Management along with the other partitions.
This tutorial explains how to create a Primary partition. when you get to the step on selecting how large you want the partition to be, I'd use the maximum size that the Partition Wizard says you can use. Partition or Volume - Create New Creating A Primary Partition In Unallocated Space
EDIT: I see Arc beat me to it! He always was faster on the keyboard!!!