I've created a test certificate in https://www.cryptopro.ru/certsrv/certrqma.asp
I'm trying to use the certificate to sign data, but I'm not succeeding.

How can I use JCP to access the private key?

I have searched everywhere for information about how to do this, but with no success.

Could you help me with this or point me to documentation of guidelines where this is explained?

Thank you very much!

I'm trying to use JCP to sign data that is sent in a REST API request.
I have used https://www.cryptopro.ru/certsrv/certrqma.asp to create a test certificate that I could use to sign the data.
But, I'm not sure exactly how to use it with JCP.

The link you provided seems to have some useful information. I'm going to look a it carefully and try again with JCP.
I'll come back if I fail to progress.

Thank you very much for the help!