Gosh, this has to be the most basic thing in the world. So I'm using CC3, I am making a woodland village. I've got some symbols placed but I need to make one symbol to be "over" the others. It's a tree that I want to obscure what is below it. Yet the ring of rocks and the different buildings are on top of the tree.

I figure that this has to be the simplest thing in the world, but I'm very new to CC3. Can anyone please help? Thanks.