Line Following, Obstacle Avoiding , and Victim Finding

Im an electronic engineering student ;1st year ; only 4 months into the course ; so i have only learned very basic stuff about robotics yet ;
I build this robot by using this guide http://www.societyofrobots.com/member_tutorials/node/55 ; now i want to improve the robot to follow arrows also ; what changes must i do to this design and the *coding* ? (everything is in that link i provided,coding etc) ; and also i want this robot to detect a big black spot and when it passes there ; this should stop.
I think u may need the size of arrows and the size of the spot to code it, lets just take them as x,y,z....

OK so you're aware we're using Melabs PIC Basic Pro compiler and Microchip microcontroller here?

yes; that pprogramme is written in PIC basic PRo ; thats why i posted here