You drag and drop folders around within LR on the left panel. When you do this, it actually makes the changes on your computer or external hard drive. The left panel simply mirrors what you have in your computer. You can move photos or folders around this way. If you need to move them to a new hard drive but don't have anything from that hard drive currently linked into LR the drive won't show. So, create a folder and put it onto that hard drive when asked where to put the folder. Then the hard drive will show up in the left panel of LR as that folder would then be linked. You could then move any folder to that drive as well. Be sure to do everything from within LR. If you move anything outside of LR you will break the LR link to the folder.