Hi Gail, From the underneath as it will a whole lot better than trying to paint the top and keep it smart.
Another vote for painting it underneath! That way it won’t get scratched off in use or worn off with cleaning etc.
Here's a video that might help - https://www.youtube.com/watch?v=aztvPCPBnmE
Gail: Underneath IS a great idea!!!
Gail,. I'd use a roller. Aloha!
Gail....You can paint the bottom with Elmers glue and food coloring. Put a drop of food coloring on some glue on a paper plate and paint from the bottom with a sponge brush. You may see streaks to start with as you paint but it will dry so pretty. Use pastels or mix the different colors in the glue.