M23, I'm assuming because they admit they're new you didn't want to blow their mind with a Ternary setup?
#include <GUIConstantsEx.au3>
#include <MsgBoxConstants.au3>
#include <ButtonConstants.au3>
$hGUI = GUICreate("Test", 500, 500)
$cButton = GUICtrlCreateCheckbox("OFF", 10, 10, 80, 30, $BS_PUSHLIKE)
GUISetState()
While 1
Switch GUIGetMsg()
Case $GUI_EVENT_CLOSE
Exit
Case $cButton
GUICtrlSetData($cButton,(GUICtrlRead($cButton) = $GUI_CHECKED) ? "ON" : "OFF")
EndSwitch
WEnd