To write an application to the sub-divisional magistrate in Hindi, start with your and recipient's details in the top-left corner. Follow with the subject (विषय), formal salutation (प्रिय/मान्यवर), and introduction stating the purpose (उद्देश्य). Provide details, reasons, and any supporting documents in the main body. End with a polite closing (आभारी रहूँगा/सादर) and signature.