How to theme taxonomy ticker?

How to theme this ticker? I want to set something, for instances, background color, width and height of the block so that it can match existing theming.

I see instruction below from the readme.txt of the module:

Position the taxonomy_ticker block in your theme using something that looks like that :

#block-taxonomy_ticker-0 {
  position: absolute;
  left: 200px;
  top: 20px;
  background: transparent;
}

But I don't know where this code should be put and make it work. Any explanation in more detail?