Will Google find my new pages?

I have just re-built my site using WordPress, it was with RVSitebuilder.

Do I need to do anything (if so how?) so Google finds my new pages?

My old pages that show up in Google end in .php

My new pages are without the .php

I am using Yoast for my SEO

 

On same domain? Maybe to use 301 redirect?

 

I suggest you enable an XML sitemap with Yoast, and submit both your Sitemap and RSS feed to Google and Bing.
Depending on your website, they should pick it up in no time. Mine is usually indexed by Google in 3 hours.

 

If I'm getting right he had site indexed already and now he has changed url structure. Google webmaster tools will record too many errors which should be fixed with permanent redirection.

 

The same content on different URLs creates duplicate content issues. You need to 301 redirect the old URLs to the new ones.

 

Then a 301 needs to be up in place.
Apart from that, they're good to go.