automatically creating multiple pages for blog

Hi,
I started a blog and it is currently on a single page. I've noticed it's started to slow down the speed at which the images show up when you visit. The solution, I want to build out pages that all the content isn't on one main page. Is there a way that I can set up my blog to automatically do that, say after 20 posts of so have the last post automatically move to a new page and automatically have the pages building as I continue to generate posts? For reference here's the link to my current site www.whereiswndy.com.

Thank you in advance!