There are two ways to add a brand new electric guitar track to your GarageBand project. You can start from the New Project template or you can use the Add Track feature.
Option 1: Start a New ProjectFrom the GarageBand window, select New Project. Click on Electric Guitar and then click Choose.
A window will open which lets you set the name, location, tempo and other information for your new project. This information can be changed later as well. Click Create.
Your new electric guitar track will automatically open in a new project window. GarageBand will provide default amplifier combination settings. You can start playing your guitar after you've plugged it into your interface.
Option 2: Add a New TrackYou can add a new electric guitar track by clicking on the Add Track button in the bottom left corner of the GarageBand project window.
A window will open with instrument options to choose from. Select Electric Guitar and then click Create.A new guitar track will appear in your music project. Garageband will provide a default amplifier and pedal combination.
Changing Input SourceTo change the input for your guitar, double click on the amplifier in the right sidebar. A red box will appear below it. Click on Input Source and scroll to the correct input for your instrument interface.