Writing C codes for a line following robot project

hi. sorry to hijack your thread but i need help urgently.
im doin a school project building a line following robot.

im having trouble looking for the codes online for some time already.

is there anyone out there who knows how to write such codes to make the robot follow the black line?

im using 16f84A IC
im using SourceBoost to write C codes and using WinPic to transfer the codes into the IC.

help please.