You must first select a region before editing it. Selected regions are highlighted in the Wave View area, Overview, and Regions list.
Click the region name in the Regions list or the waveform in the Wave View area.
Note: You can select more than one region by either Command- or Shift-clicking the regions. You can also drag across several consecutive regions in the Wave View area.
When a region is created, it is assigned the name of the source audio file by default. Double-click the region name in the Regions list, and type in a new name.