Creating a SSH Key pair - public and private for my Windows 2008 server app so it can communicate with a partner sftp site

[ML Harmon]

I have a Windows 2008 server that runs an application I use to transfer
files to my business partner's site via sftp.
I need to generate a SSH key pair with openssl and then send my partner the
public key while I keep the private key.
I don't know how to do this with openssl, can someone help me?