The Handyboard has a lot of ports, built in H-bridge drivers, LCD display, and other amenities. All three products have helpful user mail lists via Internet. The control strategy you code into software depends partly on your robot design and its operating modes, partly on how you choose to locate and get to the candle. The contest goal is to extinguish the candle in the shortest time. If your robot isn't that fast, you need to be more efficient in finding and getting to the candle.
Most robots pick a fixed search pattern.
That is, the robot will advance to room A, search for candle, if not found go to room B, etc. until the candle is found, then advance to within 12 inches and extinguish it. To win, you need to solve these strategic problems. If this is your first contest, you can concentrate on the basic goal of putting out the flame as quickly as possible. Whatever your level, the biggest challenge is building a robot that can negotiate the maze without crashing. Fewer robots have problems detecting the candle or extinguishing it, but it does happen.