If you did not set up a Rescue email address:
1. Go to Express Lane and select 'iTunes' from the list of 'products' in the middle of the screen.
Then select 'iTunes Store', and on the next screen select 'Account Management'
Next choose 'iTunes Store Account Security' and fill in that you'd like your security
You should get an email reply within about 24 hours (and check your Spam folder as well as your Inbox)
2. Once your questions have been reset, and you set up new ones, also set up a RESCUE EMAIL ADDRESS, so if you forget them again, you won't have to go through all of this.....
Hope this helps!