Basically I want to know how to send the image to the back on dreamweaver so that I can place other images on top of that image.
for example put in your css code #imageid { z-index: -1 } so that image will be in behind,but first must been positioned
Using absolute positioning is not a good idea... To overlap images i like to set it as background-image in the containing div if more than one overlap like 3 4, add more divs inside it. Then you won't get any cross browser probs.
Using Z-indexing is a bad idea; it's support is shady at best. I would do as 007c mentioned: create a container DIV that has a background image. Inside that div, you can place other dividers or images.