To generate a sound, write a function f(t). For example:
sin(t)+sin(t/2)
The variable 't' is scaled such that sin(t) will produce middle C. The amplitude of the wave is scaled so that sin(t) is audible. Another time variable, 's', is available for convenience: 's' is equal to the number of seconds that have passed.
The math functions available are on display to the left. Here is documentation for them. Some python constructs are also available (if, in, etc.) if you can figure out how to use them. Some restrictions apply. Have fun!