Not Cathe here, but just butting in!
Retracting shoulders is pulling them back and down. At the same time, your chest goes up a bit. Think of it as very good posture. It's more "erect" than many people usually stand, but don't exaggerate to the point where you really feel like you're struggling to hold it. It should be firm, but not "pinched". I've personally found that it's very important to use shoulder retraction when doing upper body work (with the possible exception of push-ups)because it helps keep everything in my shoulder gliding smoothly. Pulling them UP will not only reinforce bad posture, but put your shoulder in a bad mechanical position (which is why I answered your question, I'd hate to see you continue doing something that could injure you).
I find it sometimes helps to get retraction down by first doing some shoulder rolls (forward and back) to warm up the area (and "get its attention!") then do another backward roll and hold in the back and down position.