Running a Raingutter Regatta or Space Derby with the software isn't much different than running a Pinewood Derby type race.  In the Software Settings screen, select the appropriate race vehicle and set the number of track lanes.  If you are not using a timing system, then also set the scoring to be Points.  Then when you run each heat, use the Manual Entry option on the Racing screen to enter the number of points for each racer, based on their finish order.