If your filtering needs are not sufficiently covered by the standard filter bar, click the Advanced button to open the Device filters dialog. From here, you can find specific instances of what you are searching for (the standard filter finds whatever contains the phrase you are searching for - for instance, searching for TDC as Operator finds both TDC and TDC Mobil), you can add other operators (for instance not equal, greater than, smaller than), and you can search for devices that belong to specific groups.
Make your selections in the Column filter tab or the Group filter tab, and click Apply. DME executes the search. Your selection criteria are shown as blue bubbles along the top edge of the page:
You cannot combine advanced and regular filters.