There might be several reasons your school is not listed. If you do not attend a high school in North Carolina, you may have created your account on the wrong website. Go to AthleticClearance.com and select the correct state your school is in and create a new account. You will be able to use the same email/password combination to create a new login for the correct state.
If you attend a high school in North Carolina and your school is not listed it might be because you are choosing the wrong school year or your school has not finished setting up their account. Make sure that you choose the school year that your student is going to be participating in.