When you finished configuring the Server Settings, you need to set up your users and groups.

Users can assign tasks to to other users in their groups. To let users collaborate, you need to put them together into groups.

You can do this from either direction: you can edit a group and add users to the group or you can edit a user and add groups to the user.

Once you have your users and groups created and associated with each other, your users can work together with the other users in the groups they are part of.