If you set up a Rescue email address:
Go into Manage Your AppleID, https://appleid.apple.com/cgi-bin/WebObjects/MyAppleId.woa/, select Password and Security, and click the first option (see below), and you will be able to proceed from there..... (I HOPE the first button is showing for you!)
Reset your password
You can change or reset the password for your Apple ID account by providing some information.
Select your authentication method.
Email authentication: To access your information, we will send an email to the rescue email address on file for you.
Answer security questions: To access your information, you will need to answer the security question(s) provided when you originally created your Apple ID.
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 'Apple ID 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!