As a project manager, you can approve timesheets entries made against your projects on the My Projects, Approvals screen. A weekly summary of timesheets by resource and approval status is provided there:
•select the weeks you want to approve and click Approve, Unapprove or Disapprove
•click on the hours in the Approved, Unapproved or Disapproved column to drill into the detailed entries and approve them
•change the data shown using the filter drop-down list.