Need help with inserting a Openx code into a post template

[phonexpo]

I recently installed Openx on to my forums. I have set-up a banner zone to show after the first post using the ad_showthread_firstpost template.

This works perfectly, but I want to surround the banner to look like this;

The red part would be the banner that I have already, I'm just looking for the code to surround the banner so it looks like the above picture.

Any help would be greatly appreciated.

-Patrick