In the library click the thumbnail of the file or folder you want to move. Don't
release the mouse button.
When you move a folder, all of its content moves with it.
Drag the content to its new location. This can be a folder in the explorer panel or
breadcrumb path, or onto another folder in the library.
Note: The target folder must be visible before you do the move. When you are positioned over the folder it is highlighted.
The target folder appears highlighted in the tree or the breadcrumb path.
Release the mouse button to move the content.
Important: To move several files or folders at once, or to move content to another site library, use the Move to action.To upload a new version of an existing file you need to use the Upload New Version option. If you drag and drop a file that has the same name as a file already in the drop location, it'll be added as a new file with "-1" appended to the file name.