Hi bobikar,
this is the address which is used to connect to the portal via a browser. If you don't have a name yet and you only using it for testing you could use the computer name in the beginning and change it later. In the later case you could use HTTP instead of HTTPS if you don't have a SSL certificate/don't want to create a self signed one.
Here's a PowerShell snippet for creating a self signed one for the computer name:
New-SelfSignedCertificate –DnsName @($env:computername,$env:computername) -CertStoreLocation “cert:\LocalMachine\My” -NotAfter "2030-12-31" -FriendlyName "My custom Self Signed certificate"
If you are accessing the portal on another machine you will still receive a warning. The "duplicate" computer name is there to prevent "subject alternative name" problems. There need to be two entries.
Remark:
I recreated the snippet from memory there may still be a problem.
Best regards,
Daniel