How to add Category page?

I’ve started a github pages blog here (https://github.com/CarltonW/CarltonW.GitHub.io)
The theme I used does not have a way to categorize posts or a category page.
I found this tuturial (https://blog.webjeda.com/jekyll-categories/), but I’d like to use my same template.
Any help would be appreciated.
thanks,
Carlton.

You should be able to follow that example and do it on your site within your theme, I don’t see why it wouldn’t work, it is just code.

You can style it how ever you want, the code is the important part and would be more or less the same on any site I would think. Just make a new page and have it use one of the layouts and try it.

Did you try it and there was something wrong?