Loop in category.php?

I have been banging my head against the wall all day and I am missing something and simply can’t make this work. I created a category.php file, but just can’t get it to filter my posts, so only the ones with the correct category get shown. When I go to one of the pages, for example the “In the Vineyard” category, it shows posts from all of my categories. How do I have to have the loop so I can only show those for my current category, the “In the Vineyard”. I can’t find the answer, been looking all day.

Thank you so much for any help!!!