We must follow 2 small steps:

1- Access from the menu above:

System->System Configuration-> To Web-APP --> Mobile Application Tab

We will mark the Collaborative Environment section and give the group the name we want.

2- We should go to the top menu:

Web and Networks --> Collaborative Groups --> Groups

Here, we must add all the groups we want to have conversation.

We press "New" button to create it. We indicate the name, and mark our preferences:

We insert, then go back to the previous window and edit the group (paper and pencil) to add the members.