If you're going to be a part of a coordinated plan to get artifacts, you need to mark all your villages which can be used in some way. This means, that you should mark villages which include

• army (big enough to get at least small artifact)
• catapults
• Treasury and hero
• a combination of the above.

Members

To mark a new village, click the green plus button on the Artifacts -> My villages page in the sidebar. Upon filling the village field in the form, you will see three toggle buttons, which will guide you through the process (for example, toggle has hammer if the village has army).

Leaders

Group leaders (with proper permissions) have the ability to create, update and delete villages of group members. You can see all villages created by the members at Artifacts -> Leadership -> Group villages in the sidebar.