2 Step : now click on new ad unit .
3Step : put your ad name and choose ads size , type ans backup ads and click on save and get ad code button.
4 Step: when ad code appear on screen copy this code and open your blogger blog then click on Layout and click on add a Gadget button and select HTML/JavaScript and paste your ad code and save this now see your blog your add will be appear after 10 to 15 mints.