Click here for information. If you've forgotten the answers to the security questions and can't get them emailed to you for some reason(the email may take a few hours to arrive), contact the iTunes Store staff via the link in that article.
The Best Alternatives for Security Questions and Rescue Mail
1. Send Apple an email request at: Apple - Support - iTunes Store - Contact Us.
2. Call Apple Support in your country: Customer Service: Contact Apple support.
An alternative to using the security questions is to use 2-step verification:
If you have a rescue email address (which is not the same thing as an alternate email address) set up on your account then you can go to https://appleid.apple.com/ and click 'Manage your Apple ID' on the right-hand side of that page and log into your account. Then click on 'Password and Security' on the left-hand side of that page and on the right-hand side you should see an option to send security question reset info to your rescue email address.
If you don't have a rescue email address (you won't be able to add one until you can answer 2 of your questions) then see if this user tip helps : https://discussions.apple.com/docs/DOC-4551
e.g. you can try contacting iTunes Support : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Account Management , and then try Apple ID Account Security
or try ringing Apple in your country and ask to talk to the Accounts Security Team : http://support.apple.com/kb/HE57