I'm rather new to C5 and am having difficulty understanding how Page Types connect to, or affect, Themes.

I only have the initial default 4 page types.

I downloaded and installed and selected a 3-column Theme from the marketplace. It shows up as having 3-columns in the marketplace and on the developer's website but I cannot get it to have 3 columns in our C5 (regardless of which of the 4 default page types I select).

So ... how do Page Types effect Themes?

If having another Page Type is required, from in my example for a 3-column Theme, shouldn't the download/installation of the marketplace posted Theme include a) automatic addition of the needed Page Type or b) written documentation on how to add the needed Page Type by hand?

My assumption is that Page Type directly affects the Theme. If this is correct ...

Is there a way to "turn off" or bypass the Page Type? If a particular Theme is designed with a certain layout then why try to force it to change with a Page Type function?

This doesn't make sense to me. What am I missing? Please explain. Thanks.