Remove the air from the bag by closing the zipper top until just an inch or so is open, arranging the bag so just the contents are hanging off the edge of your countertop, then sliding your arm from the edge of the countertop to the zipper to force the air out. Finish closing the bag.
Add to the water bath and cook for 2 hours. I recommend securing with sous vide magnets to keep the bag from floating and to keep the zipper above the water. Cover the bath with a lid, plastic wrap, or foil.