How to create a blog archive that shows only 1 category

I’ve been trying for hours to figure this out. I’m creating a blog archive. I only want to show posts that have the category “blog”. I first assumed the posts page would have this functionality. nope. So I built a custom query. I can’t find any way to select to show only the category I want. If I wanted to do woocommerce products everything is there. But not posts. I’ve tried everything. I’ve read that I need to make sure I use terms and I can finally select my category only now nothing works. I can’t use image, titles, excerpts. they’re all blank.

This should be default shit. You should be able to add posts and select what category you want without having to look things up for fucking hours. This shit is archaic compared to other platforms and what you can do in 2026. I have no idea what to even look for at this point. Help me!!