You must upload only public key part to the server!
If the server needs private key, it is probably its private key. I.e. the one whose public key part fingerprint you see on the first attempt. I.e. the one you use to authenticate the server. It is not the one you use to authenticate yourself with the server.

Hi,
I'm trying to use WinSCP with ssh and public key authentication. I generated a SSH-2 DSA keypair with Puttygen. I saved the private key (passkey.ppk), and also exported this same private key in OpenSSH format. The OpenSSH key was put into my server (FreeNAS). I loaded the ppk private key in WinSCP. When I try to connect to FreeNAS I get a message saying that the "server refused our key."

I'm not sure what to do about this. The same private key is used in both FreeNAS and WinSCP, but in different formats though (openssh vs ppk). I know the WinSCP documentation describes using a public/private key pair, but both software (WinSCP and FreeNAS) request private keys. What step/issue am I missing?

thanks