Use arrow keys / space to navigate menu. Use mouse to place notes when editing. Click above or below the grid to delete. Hold 'b' when placing notes to break a continuous note into chunks. Use 'o' and 'p' to adjust track volume (shown by pink bar). Use left and right arrow to scroll the editor. Use space to preview the track while editing. Use v to return to the main menu. Default tempo is 240. Increase to make the song play faster.
This composer allows multiple tracks to be played at once. Remix the project and save it as your own if you want to save music. Obviously this is not too practical to introduce into games because there is an extra editor attached and just one track list. I recommend that you find ways to record the music using stereo mix, such as Audacity (http://audacity.sourceforge.net/). Even just recording directly from the speakers using a microphone will be ok because Scratch compresses sounds.
