To add messages to a Talk:
1. Check the box to the left of a message.
2. Click the tab labeled "Add # messages to." Select the Talk you want to add the message to.
To remove a message from a Talk, click on the Talk's name beneath one of the messages in that Talk. This will take you to that Talk's page. Check the box to the left of the message and click the red button "Remove Talk messages" at the top of the page.