Remove the vacuum section of the Kirby Sentria by twisting the knob counterclockwise so that the red arrows are lined up, and then twist the lock from left to right so that you can lift the vacuum section up off.
Place the protective gray covering that looks like a "pig's snout" over the fan section of the and turn the lock from right to left to lock the machine.
Press the gray button at the top of the vacuum bag to release the bag from the handle. Push out from the bottom gray section of the vacuum bag to remove the vacuum bag.
Place the vacuum hose over the area where the vacuum bag was attached. Attach the vacuum hose by turning it inwards until you hear a click and the hose no longer moves.
Turn the machine on by pressing the "On" button with your foot. The vacuum will now be an air blower and reverse the air suction.