Step 1: New beginnings
When you open GarageBand you’ll be faced with this dialogue box. Click New Project and then on the Loops icon.
Step 2: Give it a name
Give your new project a name. From this dialogue box you can also set your project’s tempo, key and time signature, but these are all adjustable later on.
Step 3: Drag the beat
In the loop browser, click on Beats and browse through the selection. Click loops to preview them and drag your selection into the multi-track area.
Step 4: Click and click again
Double-click on your loop to bring up the track editor along the bottom. This allows you to edit and adjust your loops in greater detail.
Step 5: Drag the playhead
Drag the red playhead to the point where you want your loop to start. You might have to play it through a few times to get a feel for where it should be.
Step 6: Split it
In the Edit menu click Split to separate the beginning of your new loop from the rest of the original loop. Alternatively use the shortcut Cmd + T.
Step 7: Top and tail
Repeat this for the latter end of the loop you don’t need. If you look in the multi-track area you’ll see the loop you want in the middle of the other parts.
Step 8: Delete and repeat
Delete the parts of the loop you don’t want; you’ll be left with your newly cut loop. From here you can repeat this by dragging the loop from its right edge.