The way it works is you keep clicking through until you find a slide layout that suits what you're trying to communicate. You will then find links to templates for that specific layout. If you want to back up, click just outside the frame you're viewing. If you want to go all the way back to the top level, just click on Prezi's "Home" button (a small "house" symbol at the right of the screen).
I recommend that you view the electronic Slide Chooser in Full Screen mode.
Let me know what you think. Feel free to comment below, or within the individual "How-to" pages that are linked to from within the Prezi.
And if you like it - and want to see hundreds of examples of real-life Conference Room style slides, organized using the Slide Chooser, then check out the Encyclopedia of Slide Layouts.