Wondering what to do with that background stamp? Stamp and embellish a corner. Color combination is one of your most important choices. Here I chose colors opposite of each other on the color wheel. I've always admired green and red together, not as in Christmas green and red, but more of a lighter green and berry colors.
This card is available for purchase at: https://www.etsy.com/listing/202668450/birthday-wishes-card-handmade-stampin-up