1. Before sending message, you have to choose the contact you want to talk with. 

2. Message can be sent to the members in the organization that the administrator creates.   After choosing contacts, they will be listed in the lower left site of the Web Messenger window.  The highlighted name is the person you are now talking with.

3. The member list can be switched between "Group list" and "Personal list" by click the same button on the top of the member list.