advanced amp ads

I bought the advanced-amp-ads. How can I use an openx (reviver adserver) code in the custom section?

<iframe id='a7022959' name='a7022959' src='http://www.xxx.com/ads/www/delivery/afr.php?zoneid=18&cb=INSERT_RANDOM_NUMBER_HERE' frameborder='0' scrolling='no' width='300' height='250'><a href='http://www.xxx.com/ads/www/delivery/ck.php?n=ac879862&cb=INSERT_RANDOM_NUMBER_HERE' target='_blank'><img src='http://www.xxx.com/ads/www/delivery/avw.php?zoneid=18&cb=INSERT_RANDOM_NUMBER_HERE&n=ac879862' border='0' alt='' /></a></iframe>