Apple GarageBand '08 - Manual (Page 67)

Chapter 8 Tutorial 6: Arranging and Editing Your Music 67
If you move or copy an arrange region to a part of the project that is not empty,
arrange regions to the right move right to make room for the region.
If you move or copy an arrange region to an empty part of the timeline, an empty
arrange region is created between the last existing arrange region and the one you
drag.
If you move or copy an arrange region so that the region moves past the end-of-
project marker in the beat ruler, the marker moves to accommodate the region.
To split an arrange region:
1 Move the playhead to the point where you want to split the arrange region.
2 Choose Edit > Split (or press Command-T).
To join arrange regions:
1 Make sure the arrange regions are adjacent.
2 Choose Edit > Join (or press Command-J).
You can exchange two arrange regions, which exchanges all their material in the
timeline. You can also replace all or part of one arrange region with another one.
To exchange two arrange regions:
m Drag one of the arrange regions over the other in the arrange track.
To replace one arrange region with another:
m Hold down the Command key as you drag one arrange region over the other.
When you replace one arrange region with another in this way, the part of the region
from the left edge of the region you drag is replaced.
Editing Regions in the Editor
In addition to the changes you make to regions in the timeline, you can edit regions in
other ways in the editor. You can rename and transpose regions, enhance the timing of
regions, enhance the tuning of Real Instrument regions, and also set whether Real
Instrument regions keep their original tempo or follow the project tempo. To make
advanced edits like these, you must first show the editor below the timeline.
To show the editor:
m Click the Editor button (with scissors cutting a soundwave).