Create a new project. Click the GarageBand icon to open the program and you will see a "New Project" window. Use the options on your screen to name your song, select a tempo (speed), key and time signature. Click "OK" when you finish.
Hook up any instruments, audio interfaces or MIDI devices you wish to use. If using an audio interface, plug the device into an available USB or firewire port. If using a MIDI cable, plug the device into your USB port using a MIDI cable and MIDI-to-USB converter cable. If using just live instruments without a mixer or interface, you will need to connect computer adapters to your audio cables and plug them into your "Line-In" port.
Enable your instruments for recording. Click "GarageBand" on the menu bar at the top of your screen and select "Preferences" from your drop down menu. Select the "Audio/MIDI" tab on the pop-up menu and choose your recording method from the "Audio Input" list. You can select your USB device or just use "Built-In Input" if connecting to your "Line-In" input. If using a MIDI keyboard, GarageBand will recognize your device automatically and you will not need to change any settings. If you have no cables, you can still record using your computer's built-in microphone, but the recording quality will suffer.
Create an audio track for recording. Click the "+" button on the left side of your GarageBand window beneath your track list and a pop-up window will appear asking you the type of track you would like to create. Select "Real Instrument Track." Your track will appear as a rectangular box beneath the "Tracks" column on your window.
Record a sequence on your audio track. Click the "Record" button beneath your track list and begin recording using your instrument or voice. When you finish recording, press the "Record" button a second time to stop. The "Record" button looks like a large red circle.
Edit your recording. Click your track to highlight it, and then add effects using the "Track Info" column on the right. If you do not see the "Track Info" column, click the "i" button on the right-hand side of your screen and it will appear. This column will give you a series of options, like the ability to add reverb, echo and a variety of effects including compression, amplifier simulation and tremolos. Just click the options to apply different filters to your recording.
Create a software track. As opposed to an audio track, this will allow you to program music notes directly using a MIDI keyboard or your computer keyboard. To create a new software track, click the "+" button and select "Software Instrument Track" from your options.
Assign an instrument setting to your software track. Click the "Track Info" column and select an instrument from the list. The notes you play on your software track will sound like that instrument. For example, if you choose the "Electric Piano," the notes you record on your software track will sound electric piano sequences. You can edit the sound settings on your instruments by clicking "Details" and adjusting the effects.
Record a sequence of notes. With your software track highlighted, click the "Record" button and begin playing notes with your MIDI keyboard. If you do not have a MIDI keyboard, you can use your computer keyboard. Just click "Window" on your menu bar, select "Musical Typing" from the drop down menu and play notes using your computer keyboard. The keyboard on your screen will guide you as to where you should place your hands.
Add audio loops to your mix. Audio loops are pre-recorded sound or music sequences that you can add to any song for greater richness. Just create a new audio track and select your loop browser by clicking the icon that resembles an eye, near the bottom left corner of your window. Then choose from the different types of audio loops available on the list, such as "Drums" and "Synths," and explore the different loops available by clicking on them one at a time. If you find a loop that you would like to add to your mix, just click it and drag it onto your blank audio track.
Save your completed song as an MP3. When you finish recording all of your tracks and you want to convert your finished project to a usable audio format, click "Share" on your menu bar and select "Send Song to iTunes." You can save your song as an MP3 and import it directly to iTunes.