I need to create a grid of my different offers. Each offer has its own page. When I create the grid, where and how do I select which pages should be in there (as it should only contain my four offers, not the hello, about and whatever other page)?
Welcome to our forum.
I understand your issue, but the feature you are looking only available in pro version, you can pass page ids to display on the post grid.
Please see the screenshot of how it works.