When you open a media gallery, it is not automatically checked out. If a gallery is not checked out, you can navigate it, preview content or Web look, but you cannot add or remove, change order or edit content.
To check-out a media gallery
1.Open a media gallery as explained in Open/close a Media Gallery.
2.On the Edit menu, click Check-out.
Only one user at a time can check-out a media gallery.
To check-in a media gallery
On the Edit menu, click Check-in.