Hi,
You can use New-SelfSignedCertificate PowerShell command to create self-signed certificates:
New-SelfSignedCertificate
https://learn.microsoft.com/en-us/powershell/module/pki/new-selfsignedcertificate
On your server, please open a Windows PowerShell prompt and give it a try using the examples in the article.
Thanks.
-TP