Add-ons: How to make a theme like this website using wordpress?

I am creating a website about nuclear conferences, and I want to make these "Thematic Areas" like this site, by clicking on any "theme" it will appear on the same home page … the website link: amssnursecurityconference

These are the screenshots of this area. I want to do the thematic areas when I click on any subject. enter the description of the image here