When I create a new page…. I want to write some text on it in a box… But when I will fill in the box on the Add new page tab it doesn’t show up. Where has it gone and how to I get it to appear?

This must be so stupidly easy, but I can’t understand why it doesn’t appear. Any ideas?
You have selected the page template – Blog modern layout. Try set the template to default because it might be a problem with the blog template.