Your Media Library is where you can store any files, images and articles that you frequently use in your emails. This content is stored in your account, so that it's easily accessible when you wish to reuse it.
To Move Content in the Media Library
Go to the Comms area click 'Media Library'.
Select the file(s) using the checkbox and click 'Move'.
Choose the destination Library, and click 'Move'.
The item will be moved to the destination folder.