Hello!!
Here's how I do it...
Supplies
--Black Glossy Cardstock (either buy black glossy or use white glossy and brayer it with black ink)
--White Glue (like Elmers)
--Pearl Ex
--Stipple Brush
--Heat Gun
Instructions
Using 1/4 sheet of black glossy cardstock put a half-dollar sized glob of glue in the middle. Take your stipple brush and pounce the glue all over the cardstock - this should be a fairly thick layer. Sprinkle Pearl-Ex over the glue and pounce around with the stipple brush. Use heat gun to dry the glue. It will bubble up forming "pearls". Use this as a background.
And, here's a website with instructions and examples...
http://www.angelfire.com/art2/ccnl/32/CCNIssue32.html
Hope that helps!!
Mary