Hi there ItsPuck,
So the SSD is your primary drive while the HDD should be your secondary right? It would be nice if you post a screenshot of Disk Management. Just upload the screenshot to an image hosting website and post the link.
Most probably, you are using only your SSD. As why_wolf suggested, you will need to Initialize -> Partition and format the drive.
How to initialize a drive: http://products.wdc.com/support/kb.ashx?id=8NP5yf
How to partition and format a drive: http://products.wdc.com/support/kb.ashx?id=qFqqwK
Let us know how this goes,