Networking on virtual machine - basic level

I am creating a proof of concept using Virtualbox and Ubuntu. I have installed virtual machines. But I need some help with firewall rules and DMZ internal networks.
I would prefer if you could work over Teamviewer or AnyDesk to make configs. I guess it should be 1-2 hours of work for someone who knows what to do.
Please place your bid if you can assist. Entry level experts are welcome.

Thanks