So i got a 3pi robot that my buddy is board of…n i have decided to learn about this thing. He gave me the software ect. I am trying to program this thing to do PID line following but cant get the jist of the whole thing. Anybody can share some views or sample code if possible. 
Hello,
Have you taken a look at the example of PID line following included with the Pololu AVR Library? That example and several others are described in detail in the 3pi User’s Guide.
-Paul