Using PowerShell
From Windows 8.1 and Windows Server 2012 R2 (Windows PowerShell 4.0) and upwards, you can create a self-signed certificate using the new New-SelfSignedCertificate
cmdlet:
Examples:
New-SelfSignedCertificate -DnsName www.mydomain.com -CertStoreLocation cert:\LocalMachine\My
New-SelfSignedCertificate -DnsName subdomain.mydomain.com -CertStoreLocation cert:\LocalMachine\My
New-SelfSignedCertificate -DnsName *.mydomain.com -CertStoreLocation cert:\LocalMachine\My
Using the IIS Manager
www.domain.com
or subdomain.domain.com