It's pretty much the same as using any non-LetsEncrypt certificate.
On the Security tab on the Settings tab of the web server
1. Put something in the "CA Account" entry. On some servers I literally just have the word "something"
2. In the "Domains" box, put your domain name. Do not put the star or any prefix. If your wildcard is for *.propergary.com just put propergary.com
Next question is what format of certificate and private key you have. You need both. If the client just gives you the certificate he's purchased it won't have the private key and won't work. If it's in PFX or PEM format it will contain the private key but you'll need to split it into separate certificate and private key files using OpenSSL.exe
This incantation should work:
Openssl pkcs12 ?in MyDomain.pfx ?nocerts ?out MyDomainEncrypted.key
Openssl rsa ?in MyDomainEncrypted.key ?out MyDomain.key
Openssl pkcs12 ?in MyDomain.pfx ?clcerts -nokeys ?out MyDomain.crt
Note that the second step in this process will create an unencrypted private key file. That was necessary for NetTalk 11 and below and out of habit I still do things that way. NT12 supports a password on the private key but I haven't done it that way yet.
The files you've create from your wildcard certificate need to go in the Certificates folder inside your app's web folder.
They need to be named the same as what you put on the server's configuration page:
propergary.com.crt
propergary.com.key
Read the documentation here:
https://www.capesoft.com/docs/NetTalk12/NetTalkWebSecure.htmIf your app may be accessed by phones or chromeboxes I've found it's important to have the full certificate chain included (see the stuff about intermediate certificates in that link).
HTH
Jane