Ok, work with me here, since I can't see your computer screen and can't tell what you have and haven't done, I'm going to ask some basic questions.
There is a difference between registering for a scenario and registering on the ahevents.org site.
If you have never established an account on ahevents.org you won't be able to register for the scenario. Signing up for the scenario does not register you to the site.
When you hit the "login" button, there is a link to create an account under where you would normally put your login and password. If you have created an account, there is also a link if you forgot your login or password.
This is not the bulletin board account you are using now. They are completely different.
Have you ever created an account on
www.ahevents.org?If yes, have you selected the link regarding forgotton login or password?