What is my duty and the duty of the tribe to advise it, given that I am one of the descendants of the Companion Uthman ibn Affan?

Every Muslim must advise their people, tribe, and the general Muslim community on what is good for them. If you are a descendant of the Companion Uthman, may Allah be pleased with him, then you are most worthy of adhering to his guidance and inviting to his way, and the way of those who were with him from among the companions of Muhammad, may Allah's prayers and peace be upon him.