How do I switch to Dark Mode?

[DanielTheGamerYT]

Hello, I haven't been on the site in a long time and I've recently discovered about this new "dark mode". I've been searching for a way to switch into it to see what its like, but I haven't found anything so I decided that my best option would be to ask about it here. How do you switch into it?

 

[cupidcreep]

At the bottom of the page there is a little thing next to 'contact us' that says 'theme.' Click on it and choose