How to edit the HTML of the forum page (possibly stupid question?)

I would lite to animate the h1 element

of my forum with an animation from here
https://animate.style/
but i need to link this in the head tag

<head>
  <link
    rel="stylesheet"
    href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.1.1/animate.min.css"
  />
</head>

and to be able to edit the classes of the elements I would like to animate

You have two options:

You can add it on Administration -> Appearance -> Custom Header
Add the needed css code to your custom css (Administration -> Appearance -> Custom CSS)

I think the 2nd is the best option for it. So you can learn some CSS and understand what is happening there.

Spooonky Done the second way 😃 I already know a bit of CSS! Thank you!