Please anyone know about ads banners.. how do we implement in the unity3d free version...

How do we implement ads banners in unity3d free version … its driving me crazy …i am new to this coding dept i really need help … i used THIS package but its not helping me out … may be i am missing any step … i signed up at AdMob got my publisher id which is writting on the top right side on the screen after signing in … i added my game app. and they give me app id … which part i miss i dont know … or is there any other solution …kindly suggest … i am like in hell . … kindly help …:cry:

To use admob you have to download their SDK and include it in your Unity project.
Here’s the link for a download and a great step by step tutorial how to integrate ads to your project.