The concept of BeatForge is simple. Every button on the grid triggers a sound. Touch to turn the button on (green). Touch again to turn it off (gray). The buttons do not play a sound when you touch them, rather they play when the orange sequencer bar reaches them. The upper half of the grid is dedicated to melodic sounds, like bells and synthesizers. The lower half is dedicated to percussive sounds, like drum kits.
On the iPad, the entire grid is shown in one screen. On the iPhone, you can use a pinch gesture to either zoom in to one of the four corners of the grid, or zoom out to see the entire thing.
Swiping downward will reveal the settings. These are not just prefereces, however, they are part of the instrument. All of these controls work on the fly, allowing you to change and develop the music as it plays.
The far left buttons allow you to choose new melodic sounds. Just to the right of them are 9 different chords, and these will change the actual musical pitches you hear. Don't worry if you don't know what the different chord symbols mean; each one will simply create a new mood and feel for the music. Selecting the shuffle button will automatically choose a new chord every time the sequencer cycles through the screen.
On the right there are different percussive sounds to choose from, as well as a pause/play button and a clear button that will reset the entire grid. You can also change the tempo of the music by moving the slider.
You can name the song you're working on by tapping on it's title in the top right corner. Next to the title is an arrow that will bring you to the save screen. Here you can create new songs (your old song will be saved automatically when you do this), duplicate existing songs, or delete songs you no longer want.