I'm trying to walk through some things highlighted in a Lightning migration assessment that was provided to my company.  

A couple of the things I'm looking at right now are the visualforce pages and the installed package for Pardot.  

1.  I looked at a visualforce page for Pardot and I see the checkbox "Available for Lightning Experience, Lightning Communities, and the mobile app" but I am unable to check the box.  I was wondering how I make the components in the Pardot package Lightning enabled.

2. I have a visualforce page that I created and I checked the box "Available for Lightning Experience, Lightning Communities, and the mobile app".  I then navigated to Lightning and I see the VF page is there but it still has the Classic styling.  I'm an admin.  I don't code.  How do I give the page the Lightning style?  Or is it too complicated and I should just leave it as is.  I thought the styling was applied with a snippet of code, but I'm not finding that in my google search.