1. Sign up — First of all, you’ll need to sign up for a Feedburner feed if you haven’t already.
2. Go to Feedburner.com and login
3. Click “My Feeds” in the upper-left-hand corner
4. Then you need to input the blog url to burn a feed.
5. By following the instructions one by one, you will get a feed address
6. Go to appearance->widget
6. Please copy this url to Feed Url field inside Feedburner Email widget.
7. Click the ‘Save’ button.