How can I make my image stop repeating at a certain point in HTML or CSS?

I am making a website using CSS & HTML for a project in my Advanced computers class and I cant figure out how to make a repeating image stop at a certain point (About 500px from the top maybe? Or atleast below the title).

I will post a link down below to my Html and CSS, I am trying to make the llama's clip off when they hit the Horizontal line. I know a little JavaScript so if you could show me how to do it in JS that would be great too. THANKS!

Link: http:// http://ift.tt/1FzcP5U