Add Network to a Proxmox VM with internet access but not accessible from outside

Is there a way I can add a network to VM on proxmox with:

1. VM has internet access (through host? I'm not sure if this is how it works)
2. VM need not have an external IP and need not be accessible on internet. (I have limited IP's rented from the dedicated server provider)

Am new to networks so any help would be greatly appreciated.