[SOLVED] Trying to understand page layout.....

I am still new at HTML, and have been very happy with the theme. I've learned a lot, and am progressing with my new site.

I am having trouble accomplishing a look that seems to be normal with other sites; having a fixed-width content area in the center of the screen, with a color background on either side of the content to accomodate different width monitors. Please see as an example, http://www.enclaria.com/, done in WP with a premium theme (Essence from iThemes). The color (and textured) background fills the page regardless of the monitor width, and when the window is resized, the content remains centered and not cut off until the resize is narrower than the content.

With every conceivable combination of parameters on the Layout page, I am unable to accomplish this desired behavior.

It surprises me that I can't find a forum post on this topic. Maybe I am just a bit slow.....

Thanks.