Trying out drag and drop themes

I am currently using a child theme of twenty twelve on my site at https://www.catholictravelblog.com. I want to use a drag and drop, but cannot figure out how to play around with the layout without making it active. I have Headway theme installed and want to learn how to use it. Something simple that I am not understanding I suppose.

The choices I see when I go into themes.appearance are:

activate live preview details delete

Is there a way to design it without changing what people are seeing online?