You'll get more responses if you upload your page to the web and provide a link here so we can see it in our browsers.
You can't use an image as an overlay, and then put text on top of it. Once you "insert" the image into a div, it becomes a piece of content, and will be separate from text.
You need to set the image as the background for the div in order to put text on top of it.
My image is 960 by 1000px and I would like to place a text box right on top.
Web pages must be flexible to accommodate varying amounts of content, user text sizes, displays, etc...
If you limit page height to 1000px, you've painted yourself into a corner because web page height is determined by content; not explicit height values. Page width is whatever you want it to be based on your target audience's needs.
Use your graphics editor to slice up your image into segments.
Taking a Fireworks comp to a CSS Layout in DW
Part 1 - Initial Design
Part 2 - Markup preparation
Part 3 - Layout and CSS