I'm using SUSE Linux 9.1 and I can use KGpg to sign and encrypt email. That part I know how to do.

My question is, how can me and a friend have a encrypted email conversation with out sharing our private keys with each other?

You each send each other your public key. You never send anyone your private key ...

Sure that works when signing email, but what about encryption. I tried sending my self a test email and I had to type in my private key to decrypt the email on the same computer.

So are you telling me that I can send some one a signed and ENCRYPTED email and that they can read it if they have my public key? If the answer to that is so than it would seem pointles to encrypt email if all some one has to do is download my public key from those pgp servers, import it to there computer, intercept the email and decrypt it and read my email.

I think a better understanding of PKE is in order for you ... read this

Much informative, thanks for the link.