Certificate for VIP

Our configuration has a Public VIP is mapped to a private address for access to a webserver with an SSL certificate. This was create by the firewall administrator, which I am not. The connection works but we receive an "Invalid Certificate" error when connecting as we are using the VIP  IP address instead of the private webserver name. The admin has requested I look for documentation on getting a certificate for the VIP. I am new to this, can someone please point me in the right direction?

thank you!