Since you're new, you probably don't want to start figuring out how to use Shapes and gussy them up to look real. Photoshop ships with some. However, to make it real easy and real cheap, google "digital scrapbooking supplies." These online stores practically specialize in the sort of thing you're looking for. Using their search engine for "journal elements" and maybe even as specific as "banners" or "scrolls," you'll have plenty to choose from. All the elements sold in these stores are JPEG for backgrounds, and PNG for everything else to preserve transparency, so they should work just fine for you as an overlay.