Just install the extension. Click on the left side at “Extension & file tools”. Select one of the 8 modes (see top left).
Note: you need admin rights! The link appears under the “Admin tools”.
Note to tool 1 (shows you all pages where you use extensions): you can add more CType´s here: “Or exclude elements with this CType value:”. Separate them by a space character. E.g.: “gridelements_pi1 mask_button mask_box”.