To do this you will Select the Configure button from the Dashboard and then put a check in the box on the Right side of the screen that says "Launch next time using the Primary look and feel."
Don't worry I have included this video:
When you open up ActivPrimary you will immediately notice the new look. One thing to keep in mind is that some things are not in the same place as they were in ActivInspire but all the same features are still intact. When you look at your Browser window you will notice that the two icons are missing for your Page and Resource Browser. Don't worry they are now located along the bottom of the floating Toolbar. Now since the features are the same and just the look is different there is no new learning curve with the software. Everything that you could do in ActivInspire you can do in Primary. However, if you need some additional assistance you can check out resources on Promethean Planet and videos from YouTube.
images from ActivInspire and ActivPrimary
video by: eherreid