It depends on how you have things set for naming in your Configure Track Header dialogue box. Without getting to bogged down in all the nuances of this - the following will probably work for you:
* Like an audio track, just name the track in advance of recording on it - and the newly recorded regions will take on the track name.
* If you want to rename a region after the fact, click on it with the text tool and rename it directly in the main body of the Arrange Window.
* Or, if you want to rename a region after the fact, select the region and rename it from the region parameter box in the upper left of the Inspector.