Hi Ohio Kim,
I agree with everything mla2ofus said. I never heard of planting into just manure either. Besides, that would be waaayyy too rich for many plants. Another thought is that manure is organic matter and will continue to break down and shrink down. In a few years you will be right where you started from. You will need to purchase SCREENED topsoil to work in with SOME manure and compost. If it were my new bed, I'd use 60% soil to 40% compost. I'd also go no higher than 18" so you can sit in the edge comfortably and weed.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.