MDTF When Creating a Menu?

Hey everyone, I am new to WP. Sorry for the rookie question. I am trying to configure the blog/site and when creating a new menu for the main nav bar, you have the option to select all or just one being mdtf or sample page. I undertsand that mdtf helps your meta search results. Do I select all or just choose one? If you select all it obviously gives you both in the box to the right. Your suggestions?

Thanks a bunch,
Zeroblog