Open GarageBand. To create a new blank song project, click “File” at the top of your screen and select “New.”
Click the “Loop Library” button, indicated by an eye symbol near the bottom of your project window, to open your Loop Library. You will then see a list of loop categories such as “Drums” and “Strings.”
Select a loop category with your mouse. To hear any individual loop on the list, click it with your mouse. Click it again to stop it after you finish listening.
Drag loops onto your project window. When you hear a loop that you want to include in your song, click the title and drag it directly into the main project space in the center of your screen. A new “track” (or layer) will appear, resembling a horizontal bar. Your loop looks like a shaded region within the track space.
Drag additional loops onto your work space. For instance, if you started with a drum loop, you might want to add a keyboard melody or a bass line. When you drag loops onto new tracks at the beginning of the time line, they will all play at the same time, since your tracks represent layers.
Extend your loops. A typical loop stretches from four to 16 beats, but you can repeat a loop as many times as you need. Just hover your mouse along the upper-right corner of any shaded loop region and drag it to the right. Continue dragging it along the time line for as many beats as you need. Do this for each loop.
Connect a microphone to your computer. You can use your internal microphone or connect a USB microphone. To connect a professional vocal microphone, use an XLR-to-USB cable or an audio interface to achieve a direct connection between your mic and your computer.
Click “GarageBand” at the top of your screen and click “Preferences.” Select the “Audio” tab and choose your input source (such as the name of your USB microphone or interface) from the list. If using your internal microphone, select “Built-In Audio.” Exit "Preferences."
Click the “+” button in the lower-left corner of your screen and then select the “Real Instrument” option on the pop-up menu to create a new audio track for recording.
Connect a pair of headphones to your computer. When recording vocals, always monitor your instruments through headphones while singing into the microphone. This will prevent external feedback from entering your vocal recording.
Click the “Record” button in the lower center of your project window and begin singing as the loops play through the headphones. When you finish recording, press your space bar or click the “Stop” button at the bottom of your project window.