This card uses a technique called "Triple Stamping".
I cut some watercolour paper 3 x 3, 4 x 4 and 5 x 5. Then I layered them on top of each other with a bit of adhesive (not too much because you have to remove them from each other.) I have something called a "Rainbow Sponge" which is basically just a really condensed sponge. I put 1 drop of red, orange, yellow, green, blue, purple re-inker side by side on the sponge and then lightly misted it. Then I dragged the sponge in an arc across the paper. I then misted the paper a little bit so the colours would run. I let dry and then stamped the Seahorse all over in black ink. (Where the papers overlap the stamping will not be perfect but this will be covered up.) You now remove the layers from each other and mat them (I used a ¼" mat so I cut my black 3¼ x 3¼, 4¼ x 4¼ and 5¼ x 5¼.) Now adhere the layers on top of each other and attach to a base (5½ x 11, scored in the middle.) I added a bit of ribbon, brads and the "Happy Birthday!" sentiment.