Important : In the end of subscription you get an email to verify your mail id, to verify that the email-id you entered is yours, But only 20% people notice this mail. So it is very important to click the link to verify in order to subscribe successfully.
Read here the complete method:
1. Enter your email id.(see photos for reference)
2. Enter Human Verification Code.
3. Click on Button 'Complete Subscription Request'
4. Important step, Now you will get a mail from feedburner or google, saying that you have requested for subscription, ans will ask you to verify your email-id by clicking on a link. Click on that link.
5. If you have completed 4th step, then you successfully registered yourself.(You are among 20% intelligent people :) )