Enabling AdSense on your blog

To enable AdSense for your blog, click on the Earnings tab from the drop-down menu on your dashboard.

You’ll then see the AdSense overview page. If you haven’t signed up for AdSense yet, click Sign up for AdSense.
On the next page, click the link to “Create a new AdSense account.”
Complete the application form, review the information you've provided, and then agree to terms and conditions.
Ads will not appear on your blog until your application has been approved. Once you receive confirmation that your application was approved, you can control the ways the ads show up on your blog through the settings on the Earnings tab at anytime. It’s up to you whether or not to show ads, and where on your blog to display those ads (sidebar and posts, just sidebar, or just posts) if you’re using Traditional templates. Dynamic Views users can skip this step, as we’ve already optimized ad placement for Dynamic Views templates.

To learn more about monetizing your blog, check out About the Blogger "Earnings" tab or About AdSense for your blog