There are no stupid questions in bowfishing.
I still have my original drum reel somewhere around here.
The retriever reel has a plasticbottle that holds the line. It comes out when you shoot the arrow with no buttons or anything to push ahead of time. When you want to reel the line in, there's a lever you can squeeze with a finger or two (while still gripping the bow) and a handle you crank with your other hand to reel the line up into the bottle. It doesn't have gears like a spincast so it's a tad slower to reel in compared to a spincast.
Generally, if you get a decent sized carp, it's best to just pull the line in by hand like you would with a drum reel. Then, once the fish is on the stringer, just reel the line up into the bottle and you're ready to shoot again.