This Tutorial From Raptivity Blog :
You can add an attractive interaction on any slide of the PowerPoint. There is no gimmick in it but certainly simple guidelines to be followed. Read them and save the hue and cry.
a. Open the PowerPoint presentation in which you want to add the interactivity. Go to the slide where you want to add the interactivity.
b. Click the “Microsoft Office” Button, and then click on “PowerPoint Options” as highlighted in the screenshot below
You can complete the tutorial at the source page here :