You can put those directly into your media. If there's a plastic wrapper, take it off and bury the cube so the top is just below the surface of your media.
I use the cube wrappers as a notepad for each plant. Date the clone was cut, date put in to flower, etc. When I plant cubes in my Fytocell media, I just slip the wrapper upward off the RW cube and leave it around the stem, sort of like an ankle band on a bird.