I am not exactly sure what you are asking. If you simply mean how do you move files between different hard drives the easiest way is to right click and either "copy" to make a copy or "cut" to actually move a file. Then in the destination folder right click in a blank space and select "paste".
To create space uninstall unused programs or move any large files ( movies/music ect. ) to a different drive than C:
I have to say if you are not sure how to cut/paste but you found Tomshardware then I am impressed. This is one of the best places on the internet for computer help so ask away. Just try to be specific as you can in any questions.