Sorry for the delay....I've got a few cakes on at the moment.
I rolled out the sugarpaste in more of a long triangle rather than rectangle. I
tried to get an idea of how tall and wide I needed it by using string to measure around the cake.
I folded the sides of the sugarpaste into the centre of itself loosely so it was easier to pick it up, and place it against the cake. It was then a matter of using a cake smoother to get it nice and flat.
Hope that helps a bit