Configuring Preview URL in Contentful In Web App

Question

I am new to contentful. I have set up a content type in the content model of the example project as Blogpost. As a second step, I added the content entry of type Blogpost. I noticed that there was no preview configured in the web app. I looked into the guide in order to understand how to set up the preview URL and I am quite stuck at it. Please find in the image below, how i setup my web preview URL,

After configuring, when I go back to the entry, and try to preview it, it gives the following error

Can someone please help, what am i doing wrong here.

Thanks, Bee