When you are at the welcome screen and click the Create Account button you will be prompted to log in. Use the credentials you were given.

Once on the Create Account screen a few simple rules apply to the displayed fields:

First Name cannot be empty.
Last Name cannot be empty.
Email Address must be at least five characters long. '@mybigmail.com' will be appended to it.
Password must be at least five characters long and is case sensitive.

First and Last name combinations must be unique. You cannot have two Jane Smith accounts even though the email name is different.

Once the Create Account button is clicked you will see either a Success! or Failed! message:

If Failed! was displayed, please read the message in the alert box and make any necessary modifications.
If Success! was displayed, the new email account may now be accessed at https://www.mybigmail.com/owa