I have often wondered how you get the sub folders of your website to show up in google search results like the attached image shows. I’m using wordpress and I’m wondering how I can get Google to Index my other pages?
They are called 'Sitelink', if you check in Google Webmaster Tools, under the 'Links' section and then under 'Sitelink', you'll have more info about this.
You cannot directly control that.
Google will display them when he will think that sub pages of your site are relevant enough.
You'll need to make sure that most of your pages are indexed (you may want to add a sitemap), then, you'll need to get proper internal links to the pages you most want to see as Sitelinks, then to get 3rd party links to these pages to (not mandatory but that helps) and then to be patient.
PR doesn't really matter there
for instance I have a small site with his home page to PR3, and it has sitelinks as I want to.
