Create a New Song File

Double-click the GarageBand icon in your Applications folder to open it. If this is the first time you've opened GarageBand, the window shown on the left appears. Click "Create a New Project."

In the "New Project" window that opens (shown left-bottom), type a name for your project. Choose a location in which to store it from the "Where" pop-up menu. The default location is the GarageBand folder inside the Music folder that's located in your Home folder, but you can choose any location you prefer.

The bottom section of the "New Project" window contains the song's Tempo, Time, and Key settings.

Tempo is the speed of the song measured in beats per minute (bpm). You can set the tempo anywhere between 60 bpm (slow) and 240 bpm (fast).

Time, such as 4/4, defines how many beats (the number before the slash) will be in a single measure, and which length of note will have a value of one beat (the number after the slash). In 4/4 time the 4 after the slash stands for ¹/₄ and indicates that quarter notes will equal one beat. In 2/2 time there are 2 beats per measure, and a half note (the 2 after the slash stands for ¹/₂) equals one beat.

Key is the central note that determines the pitch of all other notes.

Click the "Create" button to open the GarageBand window, shown below.