Hi Syed,
Try this code:
Code:
@ DEVICE pic16F84A
define OSC 4
PortB = 0 ' set port latches low
TrisB = %00000000 ' set portb as outputs

loop:
PORTB.0 = 1' Turn on LED connected to PORTB.0
Pause 1000 ' Delay for .5 seconds

PORTB.0 = 0 ' Turn off LED connected to PORTB.0
Pause 1000 ' Delay for .5 seconds

Goto loop ' Go back to loop and blink LED forever
End
I have had the high low operators fail to work for me and I do not know why.
EDIT: Make sure to hook up that ground wire to vss pin 5