OK, I think we have two problems here. The first is that you haven't entirely understood how my code works, perhaps because I haven't explained it very clearly. The second is that all through this thread, I've been guessing at what you want and what you're trying to achieve, because you haven't given me full information.
In my code, there is an x and y repeating background image on <body>. (i.e. the image repeats horizontally and vertically.) Inside <body> is the div #background1, which also has an x and y repeating background image. This div has a min-height of 800px set. Nested inside this div is another, #content. It has a 400px high background image, which is set to repeat-x only. So no matter how tall the div gets, the background image will only ever cover the top 400px. The image (standing in for your slider) is centred over the join between the two backgrounds. If you're using different sizes of image/backgrounds, then you'll need to play about a bit to get things lined up, but the theory is simple enough.
You added in another complication yesterday, when you mentioned that you wanted the body background to show through the top background (which is applied to #content). There are various ways to do this, depending on the kind of images you're using. If you're using a fixed-size, no-repeat image for the lower background portion (on #background1), then you can use background-position: 0px 400px; to position it below the other background. If you're using a repeating image, you'll need to construct it in such a way that it has a transparent area at the top, to lie underneath the top background. There may be other ways to do it, but as I don't know what else you're planning to put on the page, I'd be guessing again.
Can you work out from that how to adjust my code to fit your images? I can't be of much more help just now, because
but the two divs dosent meet in the middle of the sliderpic
doesn't give me much clue as to what's actually happening. :)