You are welcome to use this program: random numbers generator - public or a simpler random integer between min and max - public.
Here is how to call it: call random.
Here how you can use this random numbers program to generate a random string: random string.
Here is a useful spreadsheet witch act as a GuidedTrack library: Program library : Program inventory where you can find this program and more. And here is how you can access it without leaving GuidedTrack editor.