Fondant icing

[SweetPeaPods]

I've made the cake, crumb coated and it's covered in fondant icing. I would like to decorate it tomorrow with a different coloured fondant, either stars or circles. I have the cutters, and the ready made fondant but what do I need to do if that makes sense?! Should the icing be the same thickness as that on the cake? How do I stick them on?

I'd make the decorations thinner than the fondant covering but I suppose it's just personal preference? A little bit of water on the back of each fondant shape will stick it or if you can get to a hobbycraft/cake decorating suppliers you can get edible glue for about £3

Fab thanks. Water will do