How do I shade a single cell in a table?

I am trying to create a table in FrameMaker where one cell has a red background, one has an orange background, and one has a yellow backgound. This won't be a table style -- it's just a one-time table that serves as a key to certain color codes in the manual. I cannot for the life of me figure out how to "select" a single cell and apply a color to it. I also can't find a way to do this in the Table Designer, since there is no option for "just this one cell." As with my previous question, I suspect there's an easy answer to this, and I'm just not finding it in all of the resources I've looked at so far. Thanks in advance for any help you can give me!