how can I implement Admob in unity4 to gain something for android?
Follow my tutorial here.
Its two step integration.
I guess you may want to try the Admob Ads Plugin for Unity3d we made.
And good news is we have a FREE trial version - Admob Ads Plugin Universal (iOS Android) ready for you guys to download.
Download it at http://www.neatplug.com/trial?p=p-u3d-admobaduniversal .
It is the easiest way to get Admob working for you on both platforms in no time!
Any interests in other plugins we provide? Kindly navigate to http://www.neatplug.com to check out all great changes happening on Unity plugins!
Cheers.