Pressing the magnifying glass toolbar icon on the top of the screen initiates search mode. Note this icon only appears when in the "Entire Lockr" area.

Typing 2 or more characters initiates the search.

Next to the search area is a switch that allows you to toggle bewteen searching only cards and folders or also searching the contents of fields.

Search results are displayed (if there are any) and can be manipulated almost normally.  e.g a folder or card can be opened, names edited, icons changed etc but cards/folders cannot be cut or copied from the search results.