a switch and 2LED

[sayzer]

Assuming that you already set your pins as inputs & outputs; a code as below should work.
edit : Also, is it a push-pull button or a holder switch?

OUTPUT PORTB.3      'make pin an output pin
OUTPUT PORTB.4      'make pin an output pin
INPUT  PORTB.5      'make pin an input  pin

GreenLED    VAR PORTB.3     'assign a name to the pin
RedLEd      VAR PORTB.4     'assign a name to the pin
Emergency   VAR PORTB.5     'switch pin

Begin:
GreenLED = 0   'Initially OFF.
RedLEd = 1     'Initially ON.


main :

IF Emergency = 1 Then            'Someone pushed the button.
   WHILE Emergency = 1 : wend    'Wait for finger release. 
   TOGGLE GreenLED    'Change the status.
   TOGGLE RedLEd      'Change the status.
ENDIF


GOTO main