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Forum Moderators: rogerd
I haven't actually seen ads (adsense or not) displayed on a board so I don't even know what's possible.
adsense also looks quite heavily at the page title, which presumably is the name of this passworded forum; you could rename the forum, for example.
For programming help a page in phpbb is constructed using following tpls.
overall_header.tpl (/includes/page_header.php is the programming file.)
To simplify use extreme mod to have php code inside tpls. Edit overall_header.tpl and call the phpadsnew code to display your ads.
Hope it helps.
I use my own system where I do not have rotating ads but it varies only when you refresh the page. This is based on probabilistic distribution, very simple integration to phpbb.