Use one of the flatter sides of the jar as a guide and trace around it. Then cut your picture to fit. Use decoupage to adhere to the inside of the ornament and allow to dry completely.
Cut a piece off of the styrofoam ball the size of the inside of the lid. Then cover with decoupage and fake snow. Use hot glue to add a few mini trees to the top. Allow this to dry completely as well.
Once dry, add some of the small foam balls to the inside of your jar and add the lid. Then hot glue a looped ribbon to the top. You are ready to add these cute photo snow globes to your tree.