Remove your topper from the sealed bag and gently peel off the clear top sheet.
If you're using fondant icing, use a pastry brush to lightly wet the top of the cake around the edges. This will help the topper to stick to the fondant. Don't make it too wet or the topper, particularly if the fondant is a colour (not white) as too much water will make the topper transparent.
Carefully peel the topper from the backing sheet and place it on the cake. Try not to touch the picture!
Tap the edges to seal the topper on the cake.
You can finish it off by adding some sprinkles or pipe a bit of icing around the edge of the topper.