I tore it into small chunks, and decoupaged it onto the eggs. The gold standard for decoupage mediums is Mod Podge, but if you don't have any watered down white glue will work in a pinch. Don't worry about the ridges and bubbles, smooth them out as best you can with your paint brush, they flatten out a bit as they dry.
This entire project cost me nothing, because I had all of the stuff on hand. These will be going on the mantel with another Pottery Barn inspired moss project.