Create new post, creates html link to nothing

When I create a new post, my new post shows up fine in the blog’s main page, but the title has a link to https://www.mysite.com/newpost (where mysite.com is my actual website, and newpost is the name of the new post).

after publishing the post, when I view the blog, it shows the post, and when I click on the header, it sends me to a page that doesn’t exist (there’s no newly created html file for the post).

Hmmm?