Hello @SharonRSmith,
Thank you so much for reaching out on the Community Forums! Using an AT&T account is a great way to manage your account! I would be more than happy to assist you.
If the phone number is linked to a business account you will need to set up your online access through AT&T Premier. Choose Register and it will walk you through the prompts to register for a new account.
If your mobile number is not linked to a business account and you are personally fiscally responsible, please let us know by replying in this thread.
I hope you have a marvelous rest of your week!
Jessica, AT&T Community Specialist