Hi Maruti!
If you are referring to CAPTAIN MANOJ KUMAR PANDEY U.P. SAINIK SCHOOL, LUCKNOW , admission to this school is made only once a year in the month of April to Class VII and IX only. The written examination for selection of the candidates is normally held in January every year. The actual dates of the examination are notified on the school website. The link to the school's website regarding the admission procedure is as follows:

http://www.upsainikschool.org/admissions/

But keep in mind that candidates are selected only from amongst the boys domiciled in Uttar Pradesh. Let me know if this answer was helpful and all the best for your future!