Public/Private keys

I'm trying to set up Putty to allow me to log in using pageant and
public/private keys. I've generated both the public & private keys and
have ftp'd the public key to the remote Linux server. I added the key
to pageant. When I go to log in I'm still asked for user name and
password. If pageant doesn't have the key I get a "server refused our
key" error message. I did add the private key to Putty under the Auth

What else do I need to do?