It's really easy, don't over think it.
Get a $20 Danielson pot, sometimes they come with rope and a red/white float.
Put 5-10 extra pounds of weight in there. You can buy the expensive pot weights, pour your own, or zip tie a 5# weightlifting plate on the bottom.
Get a bait bag or cylinder, it doesn't matter.
Drop it in 45+ feet of water, make sure it is on the bottom before you let go (really the only rule in crabbing).
In an hour or two, pull it. If there aren't any keepers, rebait and drop it somewhere else. Repeat this until you find a good spot.