How to change theme of the Lovelace Dashboard

My Lovelace dashboard looks pretty default (image

I’m seeing loads of people creating super nice looking ones (A different take on designing a Lovelace UI) and was wondering how to change it from this more basic look to something more advanced

https://www.home-assistant.io/integrations/frontend/#defining-themes

If you install HACS you can download themes other people have shared. Or you can install them manually without it.