How to: Assign or Remove Contacts/Agent to Contact Group(s)

Find the Contact you wish to allocate to a Contact group
Select the 
 icon
This will pop up the list of Contact Groups that can be allocated, double click on the one you wish to add
Repeat until you have added all the Contact Groups you wish to.
You can add multiple Contacts (agents) to a Contact Group at the same time. However, you cannot add multiple Groups to a Contact, this has to be done one at a time. 
To remove a contact group from a contact
Right click on the Contact Group you wish to remove
Select Delete