Rose scrambling up a tree

Last autumn, I ordered a climbing rose from Crocus (can't remember what it was called) because it was described as being good at scrambling up trees. I have an old elder tree at the bottom of my garden, which consists of bare tree trunks for the first 3 metres of so. Obviously, that doesn't look great, so I thought a rose scrambling up it and covering the bare trunks would look nice (incidentally, I also bought a clematis for the same purpose, which is planted on the other side of the tree). But how do I get the rose to go up it? Does it need support, a climbing frame of some kind? should I wrap chicken wire or something similar around the tree so the plant has got something to hold on to? And do I need to attach new rose growth with twine or something? Or does it all happen automatically? :confused: