I notice on this site that many of the cake decorations are either fondant or gumpaste? Which one do I use when??

Hi, if its circles and stars stuck on the cake and a ribbon around the cake, then I would use fondant. But if its stars or hearts, balloons on wire, pearls, then I would use gumpaste or a mix of fondant and gumpaste. When it dries, it goes a bit hard and holds the shape really nicely.

I agree with the PP. I am planning to decorate an upcoming cake with fondant circles of various sizes. However, the topper will be a teddy bear that I will construct out of gumpaste so that it's nice and hard and can sit unsupported.