Pan the map to your location, or enter an address into the box at the top. All available instruments in the area should be visible. Click on an instrument marker to see more details.
Start typing the type of the instruments you want to see (e.g. Piano) into the search box. A menu with auto-completed results will appear.
Click on the name of the instrument you want to find to display only those instruments. You can then zoom the map by typing an address into the same search box and hitting 'Enter'.
To remove the filter and display all instruments again, type in All and click on All in the auto-completed list that appears.