Make sure you have "deploy ads in frames" enabled in the main settings. When you select that option in "invocation code" the program gives you all the code for an i-frame that the ad appears in. I'm running ads on 3 sites right now from the same install of phpadsnew and it's running like clockwork. You insert the i-frame code on the page and voila, there's your ad.
I'm still kinda a newbie with the program, but I'm happy to give you any help I can. You also want to go to
www.phpadsnew.com and take a look at the admin copy of the manual so you can set up your cron task for db maintenance.
For a free site example go to
This Page. Not my best work, but all banners on this site are delivered by phpadsnew running on another domain.