How to wire and use a B10K linear LED potentiometer?
The Taiwan Alpha spec sheet page 2 for this type of pot shows a little information about the pinout.  Refer to the second “P.C.B. MOUNTING HOLE DETAIL” diagram, which apparently shows the top side PCB layout.  The LED's anode is at lower right, marked B; its cathode is lower left, marked E.  It doesn't say what L (the pin next to E) is.  The three numbered pins most probably are: 1 and 3, ends of the resistive element.  2, wiper.

If that is correct, you could attach pin 1 to 5V, pin 3 to ground, and pin 2 to an analog input.  Before hooking it up like that, however, take ohmmeter readings from pin 1 to pin 2 as you move the slider from one end to the other and see if readings change proportionately to position.

Note, the phrase “Center Dent” on the ebay page probably should instead be “Center Detent” or  “Center Click”.