Editing captions is done by viewing a gallery and clicking on the Edit Captions link. If this link doesn't appear at the foot of the gallery, you need to switch on Admin Mode. The Edit Captions screen allows you to enter text in a box under each picture. Pictures which have an IPTC caption will have a button underneath marked Set To IPTC. This sets the contents of the box to the IPTC caption.
Once you've edited your captions, the Commit Changes button saves them.
Deleting individual photos done by viewing a gallery and clicking on the Delete Photos link. If this link doesn't appear at the foot of the gallery, you need to switch on Admin Mode. The Delete Photos screen has a tick box underneath each picture. Tick the boxes for those you want to delete and click on the Delete Pictures button. Once deleted the pictures cannot be recovered.
If you wish to delete entire galleries, you can so this from the Gallery Administration screen.
Moving individual photos done by viewing a gallery and clicking on the Move Photos link. If this link doesn't appear at the foot of the gallery, you need to switch on Admin Mode. The Move Photos screen has a tick box underneath each picture. Tick the boxes for those you want to move, choose a target gallery to move them to and click on the Commit Changes button.