To create a group from the Groups page:

• In the left navigation click the Settings icon
• 
• Under Security, click Groups
• 
• To edit an existing group, click on its title
• To create a new group, click Add New
• 
• Enter the name of the group
• If you want to add agents to the group at this point, type their name in the Agents field and click to select them
• When done, click Save
• 

The detail page of the group will show you what agents are members of the group

How to add an agent to a group from the Agents tab:

• In the left navigation, click on the Agent name
• On the details page, click Edit
• Scroll down to Group and click in the field to select a group from the drop down
• Click Save.