My b2evolution Version: 2.x

Hello

I'm using the custom skin, and I want to know how to alternate the background colors from one post to the next, to help make the posts stand apart from each other. I also want to use an alternating repeating background image along with the alternating colors.

This question has already been answered thoroughly on the following post:
http://forums.b2evolution.net/viewtopic.php?t=11324&highlight=alternate+colors

However, the PHP code is written differently on the most recent release of the b2evolution software. I can't get the code from that post to work with the code from the new index.main.php page. Can someone help me re-format the code please?? Any advice would be greatly appreciated. Thanks!!