I have made similar things with this background before and I love to use it again and again, one of the wonderful things about digital.
Next add your desired stamps.
Next open the free form tool and add a wash over the stamped images. I made the opacity about 75%.
Now send your white wash layer back behind the stamps and print it out. I printed on watercolor paper that I trimmed to 8 1/2 by 11 so that it would fit in my printer.
Next I watercolored the stamp images with Aqua Painters and ink. I also printed out some text to add to the print out.