Adding a custom option foor pages

I’m trying to figure how to add a new custom field/attribute in all my pages that gets pulled through into a different part of the page.. for example I have a page with 2 sections, one is a blurp at the top of the page and the content will actually go in the center, all the pages will have blurps which i want to be able to edit at the page level. How can I do this?