How to add posts by category or tag to homepage templates

I wish to add templates to my homepage to display posts by category of topic. How do I populate these templates with articles by category or tag without going back to each post and getting the post number? I suspect the answer is to specify the template to populate by tag or category but I don’t see how to do this in the composer. I’ve looked at the theme panel too and do not see an option.

Clearly, there’s some easy way to do what I wish but I just don’t see it.

Tips are appreciated.

Please disgard this post. I figured it out. Thanks.