ldavhg I suppose the screenshot is not from another Flarum but a completely different app ?
If you want to customize the tags page, you can add background images to tags, I think many people achieved something like that via CSS only.
If you want to add thumbnails to discussions, you will first need to implement the ability to upload thumbnails because that's not part of Flarum. Then changing the homepage layout can be done via a combination of CSS and changes in the javascript templates.
If you want help on specific aspects, can you let us know what you have so far and where you are stuck ?
