I've seen some posts out here with people confused as to how to get the new driver they just bought to show up in their bag. Just follow the pictures and you'll be all set!
That's it. You can go back in between rounds and change clubs. The chart on the right shows you comparison between the club you have equipped and the club you are selecting. Look at the different characteristics of the clubs. This will help you to select a club that suits your particular game and style of play.
I have been told that it's possible to equip more than one driver in your bag, but be aware that you have to give up one of your other clubs to do it. So if you don't mind not having a 3 wood or Hybrid in your bag, go for it!