Adding AdSense or any other ad code in Blogger uses the same method.
1. Open Blogger.com and go the Blog’s Dashboard in which you want to add the code.
2. Click on Layout from the Left
3.Now you will see the layout of your blog,where you can add gadgets.So,click on add gadget from where you want the ad to appear.
I am adding the ad in the sidebar(sometimes the title slidebar may not be seen in your layout,it depends upon the template you use).
4.Click Add a Gadget.
5.Now you will see a page like given below.
7.Now you will see two boxes,one large and other small.
Leave the smaller box blank ie.,the Title.
Paste the adcode you got from your adsense account in the large box.
8.Repeat the procedure if you want to add more ads.
Hope it will help you.