My blog post about animations should help (link below) but just select the Swirl or Spin effect instead. You will find the Effect Options by clicking the Animation Pane button in the Advanced Animation group of icons and then hover over the animation in the pane and click the drop down menu and choose Effect Options.

http://www.thetraininglady.com/use-powerpoint-animations-make-object-appear-disappear/

Let me know if you get stuck.