It is a perfect project if you are new to electronics. You can have a very nice result in no time and almost nothing can go wrong.
English is only my 3th language so please forgive me if I made a mistake somewhere.
I used 2 schematics in this instructable. They both are from www.solarbotics.net so they get the credits for those
Step 1: How does it work?
Most small solar cells aren't able to make a motor spin when connected directly to it. So we need to store all the energy of the solar cell until there is enough for the motor to run. Thats where we need the capacitor for. Slowly it fills up until it reaches the desired voltage. The 1381 - voltage supervisor IC trips when the voltage meets the desired level and it puts the voltage to the base of the 2N3904 transistor. That opens the gates for the current to go through the motor and so the motor spins. At the same time the 2N3906 is opened. This allows the current to pass around the 1381 so that the capacitor can be fully drained. Otherwise the 1381 would shut down the circuit it the voltage drops below its trip - point.
Result: The flagwaver will come alive with little bursts of energy an it will wave its flag happely ever after.