I have one of those old auto reels, but there's no markings on it, so not sure it's a Pflueger or will be the same as what you have. Take a good look at the side that has that smaller knob, and see if the whole side can twist. It should turn clockwise as you look at that side.
This should wind up the spring inside. Once it's wound up, depressing the lever should allow the spool to turn to retrieve line.
That smaller knob is to release tension. You should not leave the spring under tension when not in use.
Here's the one I have:
Side view, notice the knurled edge around the side plate. (bottom, near the reel foot) The center is the smaller knob.
Better view showing the larger knob.