what you need:
plastic or vinyl table cloth
lay the tablecloth down flat in a garage or outdoors. (warning: this is messy).
Then dip your brush into the paint and use a flicking/throwing motion with the
brush to scatter the paint across the tablecloth. The harder you throw it usually
the better it looks. Continue until it is covered enough and you are happy with it.
You can use fabric paint and make it permanent if you are using a vinyl table cloth.
Let it dry and ta-da! you're done.