undrstanding the stepper motor programming

As you have seen that the initial value is taken as 66
This is because of the following reasons 1)66 can be written as 0110 0110 ;
Hence either p1.0-p1.3 is utilized or p1.4-p1.7 giving the same result .
Among the four connections of stepper except the two red wires connected with Vcc.Two pins at a time should be 0 and other two should be 1.
i.e. The program written above would give 1) 0110 0110 2) 0011 00113) 1001 1001 4)1100 1100 5) 0110 0110  you can check the result by multimeter