Introduction to GuitarIf you are a beginning guitar player, you can watch GarageBand's built-in Introduction to Guitar Lessons to learn some of the basics.
Access the Lesson
In the GarageBand start window, select Learn to Play. The Intro to Guitar option is best for someone who doesn't have much experience playing guitar.
Lesson Overview
The GarageBand lesson timeline is broken down into blocks of each specific subject. The subjects are: Learn, Acoustic Guitar, Electric Guitar, Holding the Guitar, Tuning, Picking and Strumming, and Strumming an E Chord.
Tuner
You can access the built-in tuner at the top right corner of the window. This will tune your instrument without requiring you to plug in an external one.
Mixer
Access the Mixer at the top right corner of the window next to the Tuner. This will allow you to adjust the settings for each input in GarageBand.