I don't know if picbasic accepts this code or not, but if you run it like that you wont see the leds do anything. They will light and go out before you even notice...
anyway, if picbasic does accept this code it will be inefficient anyway. Try shifting the bits in port B for better code.
loke this
TRISB = 0
N var byte
PORTB = 1 'light the first led
for N = 0 to 7
'if you want to see it all happen , put a pause here (pause 500 for half a sec)
PORTB = PORTB << 1 'shift the bits in portB left
Next N
Pause 10
PORTB = 0