Hello,

First Stage: It has to be attested by your school Principal . And normally it is routed through your school only. For Second level, you need not to apply , you will be receiving the admit card from NCERT (http://ntsehelpline.com/contact-information-ncert-ntse/) for the second stage.

If your school does not register for NTSE, you can download the NTSE application online from the official website or get the hard copy from the Liaison officer of your state. You can obtain the form online but will have to submit it offline only to the liaison officer since you school is not involved. You can check for the concerned officer in your state and apply for NTSE by

LINK- https://www.ntsehelpline.com/ntse-liaison-officers-lists/

I hope this helps.

All the best!!