Hi, yes you can do groups with OpenFire either by creating “persistent rooms” or by choosing contacts and adding them.
Remember that OpenFire is just the server that handles groups, users and rooms plus the serious behind the scenes stuff.
The easiest way is to install OF, log in and create your group of users. Don’t worry right away about the rooms, etc. Then look for a client application that will do what you require, I do video conferencing so I use the Jitsi client in-house and I use OpenFire Meetings or OfMeet for external meetings with clients.
OfMeet allows me to conference with clients without them having to install a plugin or client, plus it allows me to share my screen with participant’s.
If you go to the plugins tab you will find the plugins required with a good description to them.
If you’re using a windows server make sure “Advanced Firewall” rules are modified and make sure your WAN gateway is a good one that can handle NAT for UDP and TCP traffic if you need outside clients to connect.
Also it’s good to look around on the forums, there’s a lot of good Q&A AND very good people.