When you click Agree, you will get the registration form. Please fill out all the necessary fields. For User Name, you can use your first name, nickname, or full name. Choose it carefully. User name is case sensitive so decide whether you want it all upper case, lower case, or initial caps.
Most folks use all lower case for simplicity.
Make sure you type in your email correctly. This is very important. When you've filled out all of the fields, click on Submit Registration. If you've filled out all of the required fields, a Successful Registration window will appear. You should get the registration email within seconds.