To change the contents of a drop zone using the drop zone editor:
Make sure the menu with the drop zones you want to edit is showing in the iDVD window.
Choose Project > Edit Drop Zones, double-click a drop zone, or click the drop zone button (shown below) at the bottom of the iDVD window.
The drop zone editor appears at the bottom of the iDVD window.
Click the Media button, and then click Audio, Photos, or Movies.
Drag a movie, single image, or folder of images from the Media pane to each drop zone in the drop zone editor. You can also drag files from elsewhere on your computer or a connected server.
Dragging a folder of images onto a drop zone automatically creates a slideshow in that drop zone.
To delete an item from a drop zone, click the drop zone to select it and then choose Edit > Delete, or drag the item out of the drop zone.
To replace an item in a drop zone, simply drag a new file onto the drop zone.
The previous item is deleted automatically.
To move content between drop zones, drag a photo or movie clip from one drop zone to another.
The media item is removed from the original drop zone.
To copy a media asset from a drop zone and add it to another drop zone, press the Option key as you drag the photo or movie clip to the new drop zone.
Both drop zones now contain the same media item.