See page 1 Remaining part of assembly of line following robot... Fix the nut bolt set on the PCB Solder the photo resistor/LDR as shown on the image.Make sure that the LDR is at least 5mm above the ground or spot where you are placing...
Line sensing robot
The assembly of a line following robot is pretty straight forward. If you follow the silkscreen labels, you will be able to assemble it easily. The line following robot comes.