Change SIP Registrarless to SIP (Registrar)

I have setup Jitsi SIP on my desktop and today downloaded Jitsi to my laptop. When I logged in from my laptop, it showed SIP Registrarless and does not let me enter the IP address under Registrar. How do I change this to SIP Registrar so that I can put the IP address in?

Delete the account and start over and when creating it do username@server.com.

How do I know what my server is? And why do I have to do it that way? I am asking because I just simply do not know.

your server is your SIP provider. So, for example, your SIP address would be something like choonja@sip-provider.com.