PIC16F84A.. great PIC choice

if you want to acces to a specific PORT pin you must use the according PIC PIN name.

something like

read a pin
IF PORTA.0=1 then DoSomething

write to a pin
HIGH PORTA.0

or

PORTA.0=1


Write to a whole PORT

PORTB=%11100110


don't forget to set the according TRIS register.