Ok then here is the trick..
<table align="center" width="your_image_width" height="your_image_height" border="0" background="your_image_path">
<tr><td width="your_image_width" height="your_image_height">
Edit the above code properly as below..
Replace Put_Google_Ads_code_here with your adsense code.
Replace your_image_width with the width of your image
Replace your_image_height with the height of your image
Replace your_image_path with your image file's url
After editing put this code in the place you need your ads to appear(with background image)
When you choose the background colour and border colour in Adsense for content setup please try to use colours matching with your back ground image..