Victoriash:
The STS User's Guide may be your best bet. The standard rotation is three discs a week in order of the program, with one day inserted between discs. I plan on doing aerobics-only on the off days, with one day (Monday) rest. Pages 7-8 in the Guide show the suggested rotation. The Guide can be bought here: http://www.shopcathe.com/STS_Users_Guide_p/747.htm
There are variations to the standard rotation that have been discussed on this STS forum, but I leave that to others on this forum to bring these up. Good luck. I plan on starting STS next week.
-- David