[Assembly] How do I loop this?

org 100h 
 
section .text 
 
start: 
    mov bx, output  ; put address of output into BX
    mov ax, [num]   ; put 16-bit value stored at num in AX
    sub dx, dx      ; let DX = 0
 
    mov cx, 10000   ; Divide AX by 10000
    div cx          ; result in AX, remainder in DX
    add al, 30h     ; ASCII '1' = 49 (or 31h) so add 30h
    mov [bx], al    ; Store ASCII char in output
    inc bx          ; point to next char in output
    mov ax, dx      ; move remainder of last division into AX
    sub dx, dx      ; clear remainder
 
    mov cx, 1000    ; Divide AX by 1000
    div cx
    add al, 30h
    mov [bx], al
    inc bx
    mov ax, dx
    sub dx, dx
 
    mov cx, 100     ; Divide AX by 100
    div cx
    add al, 30h
    mov [bx], al
    inc bx
    mov ax, dx
    sub dx, dx
 
    mov cx, 10      ; Divide AX by 10
    div cx
    add al, 30h
    mov [bx], al
    inc bx
    mov ax, dx
    sub dx, dx

    mov cx, 1
    div cx
    add al, 30h
    mov [bx], al
   
    mov bx, output  ; get address of first char in ouput
 
myloop:
    mov dl, [bx]    ; get char at address in BX 
    inc bx          ; point BX to next char in message
    cmp dl, 0       ; Is DL = null (that is, 0)?
    je  quit        ; If yes, then quit
    mov ah, 06      ; If no, then call int 21h service 06h
    int 21h         ;    to print the character 
    jmp myloop      ; Repeat for the next character
 
quit:
    ; DONE!
    int 20h
 
section .data 
    num dw  12345
    output  db  0,0,0,0,0,0