Use the frame menu, accessed by right-clicking on any frame, to select, deselect and remove frames, and to view and/or modify frame properties.
Select Frame toggles frame selection -- if the frame is currently selected, this will read Deselect, not Select. See working with selections for more info.
Edit Frame opens the frame editor, used to modify properties of the frame.
Delete Frame deletes the frame.
To attach the frame to an image, click Attach Frame, then click the image. If the frame is already attached to an image, this entry will read Unattach Frame.
If the composition contains more than 1 frame, the frame menu contains a fourth entry:
if one or none of the frames are currently selected, the entry reads Edit All Frames. When selected, the frame editor will appear, and any changes made will be applied to all frames in the composition.
if two or more frames are currently selected, the entry reads Edit Selected Frames. When selected, the frame editor appears, and any changes made will be applied to all selected frames.
For basic information about frames, see Adding, Editing and Removing Frames. For a fuller description of what you can do with frames, see Working with Frames.