Can't attach new disk with Windows OS


I’m completely newbie and do not have any experience with OpenNebula. I’ve just bought a Windows VPS and I don’t have any idea how to manage my VM.

My VPS has 80GB in storage, but after installation, there’s only 10gb in C:\ like this:

So I tried to attach new disk to my VPS:
Here is the result: ://

But my VPS is still the same, can anyone help me out of this situation please?

(New user can’t post 2 links so I modify the third link image)