Process for NPT (Forgot to renew H4 and it is past 365 days)

Can someone help me how to file NPT along with 539 form (extension of stay)?
My son’s H4 was not renewed and was missed doing that and it is past one year. He is minor, 12 years and am doing the extension of stay with NPT.

  1. What is the form/format that NPT need to submit?
  2. Is there any process to follow while submitting it?

Thanks in advance,

I would not DYI and highly suggest hiring an immigration lawyer. Talk to your employer’s immigration lawyer and ask them if they can represent your case