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.