First thing…your page background. When you upload your page background, set the horizontal position as “center’ and this will keep your hockey background centered.
For the height of the Banner background, you mentioned it’s too small in height. To change this, you will have to install/activate the child theme for Circumference so you can make some modifications. This allows you to get updates to the theme without losing your modifications. The other option is to use a plugin that lets you edit CSS. The height is adjusted to by this:
So you would have to add your custom changes such as:
However, when I looked at your red Casper hockey banner, I think it’s best to use the Banner widget position for this one which will show up on every page (or select pages) and not as the banner background image (using the WP header feature). This way, you get a true height and width of your banner image that will also be responsive. You would get the file URL of your banner image and use html in a text widget to load the image….or an image plugin widget like someone used the other day: http://wordpress.org/plugins/banner-upload/