[Solved] How to use `extra_theme` folder?

New Lemmy admin here. I found the Theming Guide in the Lemmy docs, but it jumps directly to the 'After a theme is added' section without explaining how to add or create themes. I've searched for examples but couldn't find any configuration that includes these details.

I found hanubeki-lemmy-themes, which actually contains some good themes. However, when I copied the 5 folder to my extra_theme folder, nothing happened. Can someone guide me on how to add these themes to my instance?

Update: You should put all your css file in the extra_themes folder, each .css is a theme. For hanubeki-lemmy-themes I put all the dist and src files in extra_themes and it works. I already done this before, but my browser was [caching lemmy-ui static files for 24 hours], so when I delete the cache it just works.

Thank you Sami, it was a cash problem, I updated the post with more details