You will need to be accompanied by an adult. Correctional facilities do not allow minors to visit on their own regardless of the reason for the visit or how well you know the inmate. This applies at virtually every jail, prison, and detention center in the country.
The adult accompanying you should ideally be a parent or legal guardian. Some facilities will accept another responsible adult in that role, but the closer the family relationship, the smoother the approval process tends to be. The adult will also need to be on the inmate's approved visitor list, which means they need to be added by the inmate through the facility's visitation process before the visit can happen.
Call the facility ahead of time to confirm their specific rules for minor visitors, what documentation they require, and who qualifies as an acceptable accompanying adult for someone your age.