Still on the Crew tab of the Session Details dialog, there are fields for the following:
The comments and summary are purely descriptive for the benefit of the coach. Typically the Summary field might be used to encode the type of workout that was being done: e.g. "UT2 60 mins", or "2 x 2k race pace".
The venue can be selected from the Venue database by clicking on the Venues... button. Select a venue from the database by clicking on it and dragging it onto the Session Details dialog.