I want sign a Certificate Signing Request with PSS, but I am not sure how to do.

I am not sure if it is correct what I did, but can someone say to me how I combine the created signature with a Certificate Signing Request?

public byte[] CreateSignature(byte[] message, AsymmetricKeyParameter privateKey)
    PssSigner signer = new PssSigner(new RsaEngine(), new Sha512Digest());
    signer.Init(true, new ParametersWithRandom((RsaPrivateCrtKeyParameters) privateKey));
    signer.BlockUpdate(message, 0, message.Length);
    byte[] signature = signer.GenerateSignature(); //generation of signature
    return signature;
Message is here the Certificate Signing Request.
PrivateKey, of course, the Private Key of the Certificate Signing Request.

Sorry, the code is written in C# but I am sure it is nearly the same in Java.