I used concrete stain on bedroom floor and it did not work out. What do I need to do to paint it a solid color? What kind of primer? Thanks

You need to remove as much stain as possible and etch the concrete with acid. Is this a basement floor or a slab home?

I would wash the floor down with TSP and rinse well. Let it dry and apply a coat of oil-based Kilz-it. You can have it tinted to the color of your paint by purchasing a quart and go out to the parking lot and pour a little in a jar to give room for the tinting to be added. Go back in with your receipt and ask them to tint it. Buy a gallon of 1 part epoxy paint tinted to the color you want. You could tape off the floor with masking tape over the stain to create a pattern before you prime and paint.

Scroll down on this site and you will see where they painted designs over a stained floor:
http://www.stainedconcrete.org/color...altouches.html