On any project sheet, select one or more projects and right click in the selection and click the Assign Resources command in the right click menu to launch the Assign Resources dialog. The dialog presents a list of resources NOT currently assigned to any of the selected projects. Select one or more projects, enter a level of effort in the Effort box if desired, and click Insert. Alternatively, on any resource sheet, select one or more resources, right click in the selection and choose Assign Resources. The dialog presents a list of projects that have no assignments of selected resources.