Background color and equation.

Hello TeXmacs users,
With "Insert/Image/Draw image", I try to add a background color. I searched in The Jolly Writer, in the user manual, on the internet (tutorials)...  I can't find any way to do that. Is it possible? How to do it?
Another question. Is it possible and how to add an equation on an imported image?
Thank you very much.
Normand