Categories to Pages

I have just installed this free theme and I am a bit stuck.. I really want my ‘art’ and ‘style’ pages (which are categories) to show all of my posts corresponding to those categories, however, at the moment they show nothing when they are clicked on in the menu (and also the feature images).

Here is the link to my blog:

https://www.snaggedstyle.com

How do I resolve this problem?

Thanks!!