This will open the brief an agent screen, where you can select words for inclusion or exclusion:
The words displayed here are frequently-occurring words that are related to the words you typed in for the agent's query.
Click on the check boxes of terms you wish to include or exclude, and click on the update button to change the agent's query profile. You don't have to select terms here, but it helps if you wish to increase the focus of your query.
This will run another search, using the new settings. If you wish to cancel these settings, click on the cancel button.
Each time you brief an agent and click on the update button, the terms presented to you will be different, allowing you to steer the agent towards a specific focus.