Not hard at all. Fondant is very malleable. Lay the fondant over the cake and it will start to drape over the cake by itself. Use your hands to ease the fondant into the inside corners first and just keep working around and over. Don't trim the excess too close, then use a smoother where you can (the inside curve at the top of a two will be the hardest bit, so you might have to improvise - a straight sided glass would work). Tidy the bottom edge.
Two things I would say is, make sure you knead the the fondant well and don't under-estimate how large you need to roll it out. Use two bits of kitchen string to measure top to bottom, including the height of the cake x 2, and side to side also including twice the height.