You need to be in edit mode in order to add filter. Click on "Edit" in top dashboard menu to activate edit mode.
To add a new Filter, hover over free place and click on Add dashlet. The Insert dashlet dialog box will appear.
- Select Filter from the left navigation panel.
- Click Add to append desired filer to the dashboard.
For more information about creating Report filters continue by - Searching and Filtering Reports
Number at the end of the filter name dispays total items meeting the filter condition.
Filter will be appended to the Dashboard.