Websocket is a transport layer, you don't authenticate the client when establishing a websocket connection (just like you don't do authentication when establishing a UDP or TCP connection). You establish a websocket connection first, then do authentication when client sends a  REGISTER or INVITE message.

If you didn't setup UDP SIP messaging, I recommend doing that first to get a feeling for how to configure kamailio. You can add websocket later.

Hope this helps.