Not really a 6502 specific topic but I wanted to document this somewhere as doing development on Windows using GitHub can be a bit of a fraught process initially.

Download and install Putty (if you don't have it already). This will install puttygen.exe

Run puttygen, it should be available from the Windows Start Menu after installation.

GitHub recommend using an ed25519 type key but Putty doesn't seem to support that. Secondarily they recommend an RSA 4096 type key and that can be generated by Putty.
Click Generateand wave your mouse around until the green bar is satisfied.

Once the key is generated copy the Public-key text...

...into a new GitHub SSH Key. This can be found under your Account Settings, SSH and GPG keys: And paste the Public-Key text into your new GitHub SSH KeyAdd SSH Key and we're done on the GitHub side of things.

Back in puttygen copy the Public-Key text again, paste it into a text editor and save it somewhere useful with the .pub extension. E.g. C:\MyKeys\MyKeyName.pub Do not use the Save Public Key button from puttygen unless you know what you're doing. We're saving the OpenSSH Public-Key text just-in-case.

Next export the Private-Key for OpenSSH, again this is just-in-case......and save it somewhere secure. E.g. C:\MyKeys\MyKeyName Note the lack of extension.

The saved Private-Key should look something like this:...but with a lot more gumph in it. If things go terribly wrong the OpenSSH private key can always be re-imported back into puttygen.

Finally we need to Save the Private-Key in a form that can be used by Putty's authentication agent Pageant.Save it somewhere secure E.g. C:\MyKeys\MyKeyName.ppk and note the ppk extension.

The PPK should look something like:

Finally open Pageant from the task bar by double clicking its icon (it should have started running when Putty was installed).

And add your newly saved PPK.

If everything has gone correctly you should see your new PPK in Pageant:

And you can now talk to GitHub using Putty via SSH!