This topic is obsolete. Use the house ads feature of the plugin instead:
We’re getting this question a lot lately. The short answer is no, you can’t use this plugin to render arbitrary html as ads. I’ll try to show how to use Google DFP to serve your own creatives.
From the “New Orders” form, you can create a new advertiser. (There’s probably a better place to do this, but I can’t find it. Any DFP experts please help improve these instructions.) I called it “My House Ads”
In Delivery > Creatives, add a new creative and choose your new House Ads advertiser.
Upload your creative(s). You can use images like this:
Now you can use those creatives in your Ad Units.