How to go to sleep

[savnik]

I have this :

	DEFINE LCD_DREG	PORTB	
	DEFINE LCD_DBIT 0	    
	DEFINE LCD_RSREG PORTA
	DEFINE LCD_RSBIT 2	    
	DEFINE LCD_EREG	PORTA  
	DEFINE LCD_EBIT 3	    
	DEFINE LCD_BITS 4		
	DEFINE LCD_LINES 2	  

	DEFINE I2C_SCLOUT 1
	
	SCL var PORTA.1     
	SDA	var	PORTA.0		

	UP	    var	PORTB.6	
	DOWN	var	PORTB.7		
	CH_PAS	var	PORTB.5	 

	Input	UP		     	
	Input	DOWN
	Input	CH_PAS

    b1	var Byte
    b2	var Byte
    b3	var Byte
    b5	var	Byte

    F1	var	Word
    F2	var	Word
    F3	var	Word

    ADDR1   VAR	Byte
    ADDR2	VAR	Byte
	LOCK	VAR	Byte
	TMP	    VAR	Word
	TMP_LO	VAR	TMP.LowByte
	TMP_HI	VAR	TMP.HighByte
	PLLBASE	VAR	Word
	PLL	    VAR	Word
	LO	    VAR	PLL.LowByte
	HI	    VAR	PLL.HighByte
	PAS	    VAR	Byte
 loop:	
         Button UP,1,10,2,b1,1,MONTE	       
		Button DOWN,1,10,2,b2,1,DESCEND	   
		Button CH_PAS,1,255,0,b3,1,	CHOIX  		
		PAUSE 100                          
  	    I2CREAD SDA,SCL,ADDR2,[LOCK]       
        GoSub AFFICHAGE		               
        GoTo loop

and i want the pic to go to sleep if no button is pushed.And awake if i push any button.
I have read the datasheet but i don't know how to make
Pic is 16f84a