First of all, choose the blog that you want to put AdSense on, and go to the Layout | Monetize tab. You can get there by clicking the Layout link on the dashboard, or clicking the Template tab from the posting or settings page of the blog.
Once you're there, choose one of the three options to display your ads: in your sidebar and posts, just in your sidebar, or just below your posts.
The next page asks you to either sign up for a new AdSense account or use an existing one. Once you've signed in or created or account, you'll get a confirmation screen. If for any reason you need to switch to using a different AdSense account, click the switch AdSense accounts link on this page.
