Hi,
ADCON1 is not a command, it's register in the PIC which is used to control the ADC. When you do ADCON1 = 7 you set that register to 7 (which for the 16F737 sets AN8-13 to digital and leaves the rest as analog).

As I tried to tell you in my previous response you need to open up the datasheet for the PIC and look at the ADC section in general and specifically the description of the ADCON1 register. You'll find that setting just PortB.3 and PortB.4 to digital isn't possible.