Santander am 16 unarrenged overdraft fee?

am 16 and just recently opened an account with Santander. its a 16-18 year old account. but i have a �5.15 unarranged overdraft. i was told i woundt have an overdraft. i was just wanting to know if they will charge me a fee for this overdraft or when i depoist it will be payed off without a fee?