Garageband is a simple and straightforward application for recording, editing, and creating music.
When first using Garageband, I recorded external instruments into the application by setting up a recording microphone and recording myself playing piano, drums, and singing. By overlaying new tracks, Garageband can splice a single person playing three different instruments into one melodious track. Once recorded, each track can be individually edited for volume and pitch. One of the most fun things to do when recording external instruments into Garageband is running your tracks through the software filters to create new and interesting sounds.
If you choose to record your tracks using the internal MIDI keyboard, do not be intimidated by the difficulty of clicking the keyboard in the right place at the right time. When using software instruments, once you have recorded a few notes, you can double click the track and manually edit the timing and length of each note. Using the MIDI keyboard leaves more room for creative editing, as you have more software instruments from which to choose as well as more freedom to creatively move around notes. You don't even have to be able to "play" the music that you are creating. However, software instruments always lack that human component which can emphasize the feeling of your piece.
If you so choose, it is easy to combine both external and internal tracks.
- GarageBand, http://www.apple.com/ilife/garageband/
- Musical Instrument Digital Interface, http://en.wikipedia.org/wiki/Musical_Instrument_Digital_Interface