All of the above answers are correct for the question you asked. However, I took a look at the pattern you intend on making and it is a pretty challenging one. I only knit top down sweaters and they are a very different animal. I would highly suggest trying an easier one, first. Perhaps a five-hour baby sweater? There are loads of "easy" top down's on Ravelry and Knitting Pattern Central, etc. I love Knitting Pure and Simple patterns and they also have a seamless baby sweater for free on their site.
Even if you ARE an experienced knitter, you may want to try an easy or intermediate top down sweater for your first one because this is a new technique to you.
I have to agree. I would start out with a simpler pattern if this is your first attempt at top down, knitting in the round. It is a beautiful sweater.
Just didn't want you to be discouraged with my "favorite" kind of knitting by picking an "experienced" pattern for your first top down project. JMHO.