In Tutoom you can send private messages to any users in the session.

To do this follow these steps:

Go to Participants in the navigation bar

Click on the name of the participant of your choice

Select Send direct message

Once the private chat is open you will be able to send the desired message.

To find the chat again follow the same steps.
Your private chats will be located at the top of the Participants panel.
You will be able to send private messages as long as it is enabled in the session settings.