3 answers
I had the same issue Carol. I've found that the Lightning App Builder, and a couple other items in Lightning, don't always display fully in my browser. It's a simple fix though. The "Next" button is on the bottom right corner of the Lightning App Builder... you just can't see it. But zooming out in your browser (Control + '-') should let you see the 'next' button.
The issue seems to be related to how the App Builder window displays on the screen... and if your resolution isn't high enough, it shrinks the window and you can't see the button.
I hope this helps!
