How to open an external link on the same page in a box?

What command to use to open an external link on the same page?

I have the site.

I have the animation loaded externally to lighten the page loads main.

I would like to click the mouse on the button down of the animation (uploaded to the server individually) just without that it disappears graphics main site.

I tried with the commands:

window.open("http://www.mysite.it/animation.html", "_self");

window.open("http://www.mysite.it/animation.html", "_parent");

but I do not get what I want, because the graphics will disappear and you only see the animation. But I would like the animation to appear in the white box in the example image attached. What commands should I use? Sorry for my little knowledge of html codes. He's slowly learning. Thanks friends