4) Bait the trap. The easiest is sugar and water, but I've also read that meat works well in the spring and early summer because wasps are attracted to protein, or other options are sugar and water, water and vinegar, beer, soda, even laundry detergent. Adding petroleum jelly or cooking oil along the steep edges of the trap can cause them to lose their footing and fall into the hole.
5) Hang the trap by either taping a string to it, or affixing a screw that you can use to hang.
6) Empty the trap - but first make sure the wasps are dead by pouring boiling water in or freezing. Personally, I'll just dispose of entire trap and make a new one.
One last note, be mindful where you place the trap as living wasps will be attracted to it. Place a distance from where your kids or pets will be spending time. Our son's school place these on the perimeter of the play yard.