Firstly you need to load your planner, see Planner Loading for details.
From the list of recordings displayed you can select the ones your wish to extract by clicking the check box next to each recording. You can also right click the recording list and click 'Check All' to select all of the recordings.
Once you have selected your recordings, simply click the computer icon on the toolbar.
Once you have selected a destination for your recordings, they will start to copy to your computer.
Note that unregistered versions of ExPVR will only extract the first 200MB of each recording.