To power your robot you are going to need a 6 volt power supply. You can use a battery case for either 4 AAs or 4 AAAs. while AAs last longer, the AAAs take up less space and are lighter. you will need a switch for obvious reasons, but be sure you use one that has no more than 3 leads on it. the pontentiometer is to keep the robot going straight when it is facing the light source, or to make sure other light sources or ambient light do not interfere. Try to get a 50k pot, but go you can go higher if you think you will need to.