If you have an Adsense account, however you will have to apply for Google affiliate Network too. Google will approve your application after looking or reviewing your website in detail for a verification . After an approval mail, only you would able to show advertisement on your website . Once website is running with advertisement from Google Network and if anyone clicks on a particular ad and purchase the product then you will be getting credited with a particular commission in your Google Adsense Account . Google has so many associated group of companies and huge network of companies . You can earn easily by this method if you have good website and visitors are coming to your website .
How you receive commission from Google Affiliate Network ?
When any sale product or items is sold through your website then you will get commission and money will go in your Adsense account .
Can I have both account together Google Adsense and Google Affiliate Network ?
Yes, You can display both advertisement from Google Adsense Network and Google Affiliate Network .
If I do not have Adsense account , then Can I earn money from Google affiliate Network ?
Yes, You have to apply for Google affiliate Network account from sign up link .
How to Sign up in Google Affiliate Network ?
Before signup you just go with online help center
You can ask your questions on online help forum