A Tutorial for changing CA name of a Windows Server

I have got a Windows Server 2008 configured as a VPN server. A user will need to install the server's certificate in their trusted root to be able to connect to VPN. The certificate on the server is configured to work with current domain name of the server. I want to move this server to another domain name so I need to change the CA (or whatever that needs to be changed) I need a tutorial with pictures to exactly how to do that. I mean tutorial of removing server certificate and create a new one to work with IKEv2 protocol and then exporting it as a CER file which user needs to install.