Hey edelC, thanks! The link to the tutorial for the main part of the painting is in the first post of of this thread. They're super fun and easy!
I followed that tutorial ad then just drew on top of it with (if I remember correctly) those water soluble crayons(http://www.amazon.com/Caran-dAche-Classic-Neocolor-Water-Soluble/dp/B000YIMXMG ). You could use any opaque coloured medium though, like acrylic paints or maybe even gel pens.