Popup size

How can I change the popup size. I added a 1280×720 image but the popup is smaller and has white borders that I dont want in it. Check it in: apostrofecomunicacion.com

Here is my code in the plugin:
<img class=”aligncenter size-full wp-image-8816″ src=”http://apostrofecomunicacion.com/wp-content/uploads/2014/11/barco.jpg&#8221; alt=”barco” width=”1280″ height=”720″ />

Thanks!
Zorion

https://wordpress.org/plugins/simple-popup/