You're going about some of this the wrong way. You're using a lot of absolute positioning, which take an element out of flow and positions it relative to the viewport, or its containing element. In other words, you're positioning everything at least 200px from the left of the window:
You're also putting the large background image in an empty div. Try this approach: Make the large background image a div that contains the rest of the content. Then place that in the center of the viewport by using auto margins...
That should get you started, at least. Hope this helps...
background: url(bg.jpg); no-repeat top left;
margin: 10% auto;