If you are using just the normal takes and dissolves in the sequencer then the only way to take graphics to air is to either hit "take" on your keyboard, or double-left click the scene you're taking online. To take offline, you either have to hit take offline, or you can right click the scene and hit take offline. Once you get to using more complex scenes that utilize keyframes on a scene director, you can add pauses to the scene director then use take to resume the graphic. At the end of the scene director, you can then add a take offline block that'll automatically take it off air.
#XPression