You mean Google Adsense? I think the first thing you can do is to sign up for it. And then you'll need a website/blogsite for the site, and your site must meet the certain amount of traffic that they will require your site to have.
Create a gmail account first, then make a google adsense account. Your website must have a few pages besides about us, terms and conditions and privacy policy page. Fill the form for adsense and wait for the approval. Good luck!