To get a random number, just call Random value:
Io> Random value ==> 0.548814 Io> Random value ==> 0.592845 Io> Random value
This produces a random number between 0 and 1.
To change the seed of the random number generator, use Random setSeed. In order to prevent Io from generating the same numbers over and over again, it needs to be set when the program starts. For example, like this:
Random setSeed(Date now asNumber)