how to set an absolute position to a view (or div class)?
If you have the div's parent element set to position: relative, you can then set the ad div to be position: relative and give it and offset from the bottom. eg. bottom: 20px;
You will need to be careful that your article list div doesn't expand over the space where your ads are as they will overlap.
Post a link if you need more help.
Hope this helps.