If your trying this out for the first time, start off with a smaller sponge. The hardest part of this process is to place the icing round the sides, so the smaller the sponge, the easier it will be.
Have a cup of boiling water at hand to dip you pallet knife in for smoothing butter-icing over the sponge.
This tutoral has brief descriptions of each stage. I have tried to explain the best I can to make each process clear. If there is anything you are uncertain of, please ask, or pose a question here for someone else who may answer.
I am UK based, so my description of 'icing', is ready-to-roll pre-made. I buy it as it's easier, and tastes quite nice.