If you have a rescue email address (which is not the same thing as an alternate email address) set up on your account then 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 you won't get the reset option - you will need to contact iTunes Support or Apple to get them reset.
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 'Forgotten Apple ID security questions'
or try ringing Apple in your country and ask to talk to the Accounts Security Team : http://support.apple.com/kb/HE57
When they've been reset (and if you don't already have a rescue email address) you can then use the steps half-way down this page to add a rescue email address for potential future use : http://support.apple.com/kb/HT5312