The only way that is close to easy is to make the BoeBot into a phototropic (it goes towards a light source). Then point a flashlight in front of the Boe Bot for it to chase.
Google "phototropic robot" and "light chasing robot" for some info on how this works and google "light chasing Boe Bot" for details for a Boe Bot.
Also, search the read the threads in this SoR forum. Your question has been asked, discussed and answered a number of times.