Well, there are a lot of ways to engage in a private conversation with another person, so I'll suggest the simplest --
only 3 steps -- create a private room for the two of you and password protect it.
1. Pick a name for your room and the password you will use. Keep it simple and share it in a private message in chat with the person who needs support. Tell them to wait a minute, and then look for the room in the list by clicking on the Rooms List icon:
2. After you've shared that information with the person, click on that icon, then click on the "Create Room" button.
3. A new window will pop up asking you for the room name to create, with the option to password protect it. If you don't want to be bothered while in chat, add a simple password.
This way, you're in your own room, and others can't bother you while you're giving support.
DocJohn