Extend my C drive space in Windows 8

Your C drive on the SSD is filling the SSD.  You CANNOT expand the C Drive across two physical discs.  Your only alternative is to copy the C Partition on to your new 2TB HDD and use that as the boot disc.  You could then expand the C Drive to be 2TB if required.

Another alternative is to buy a larger SSD and use that for a larger C.

I think the main point Gonzo, and this should have been pointed out FROM THE START, is that you cannot extend your boot drive (C) across multiple physical hard drives.  All of your explanations are great in the previous answers, but lack this key detail.  Bottom line is you are talking about extending partitions on a drive, not spanning a volume across multiple drives for a boot drive and this thread was created for that purpose.

Next time, I suggest you clearly define the problem instead of telling people a a good solution for the wrong problem.  Much better to have the answer to the actual problem people are having instead of a terrific answer that doesn't apply....

Jonathan,  thank you for your criticism,  it is most helpful.

I think if you look back at my posts, carefully this time, you will see that at no point did I claim to have answered the opening question. All of my responses have been made to specific questions posted in this thread and I stand by them.

The responses I have received have been largely positive, save your own. So whilst I am sorry to have caused you any consternation, I am confident in the specific advice I have given.

I have gone through these steps.  I now have 120gb unallocated space to the right of my C: drive, but the extend drive option is still grayed out.  I restarted my computer in a desperate hope, but, alas, no help.

Any ideas on the best 3rd party software? I would prefer to not have Malware on my machine.