You can open a Learn to Play lesson in the GarageBand window to arrange, mix, and share it, as with any project.
In either the Progress or High Scores window, click the Open in GarageBand button in the lower-left corner of the window.
The lesson opens as a GarageBand project. The project includes tracks for the teacher, for the band, and for your recordings. Any changes you made using the mixing controls are preserved in the project.
Note: You can’t open some Artist Lessons in GarageBand. If a lesson can’t be opened, the Open in GarageBand button in the control bar of the lesson window is dimmed.