C# BouncyCastle generates CSR and store PrivateKey securely

Question

I need to generate a CSR from a computer using Portable.BouncyCastle library in C#. Once the CSR is created I need to store the CSR PrivateKey in the Certificate store to protect it.

Creating CSR using Pkcs10CertificationRequest is fine.

Pkcs10CertificationRequest csr = new Pkcs10CertificationRequest("SHA1WITHRSA", subject, keyPair.Public, null, keyPair.Private);

StringBuilder CSRPem = new StringBuilder();
PemWriter CSRPemWriter = new PemWriter(new StringWriter(CSRPem));
CSRPemWriter.WriteObject(csr);
CSRPemWriter.Writer.Flush();

But now, how to store the PrivateKey securely on the computer that has generated the CSR (Windows computer) so that it is persistent and use for later on decryption?

Thanks a lot for your help!