MIDI Apple Loops: You add MIDI loops to software instrument tracks, and edit them like other MIDI regions.
Session Player Apple Loops: You can add Session Player loops to software instrument tracks with Session Player as the default region type, and then change the artist and edit parameters in the Session Player Editor. You can also convert Session Player loops to audio loops by adding them to audio tracks.
In Logic Pro, click the Loop Browser button
After you add the loop to the Tracks area, you can drag it left or right to adjust the point where it starts playing.
You can also search for loops by name, key, or time signature. For more information about using Apple Loops in your projects, see PDF