new to the site

[TH3]

Hey guys, new to the site. I'm a wannabe do-it-yourselfer that has a lot to learn. I have a few questions that I was hoping you guys can help me with. I have a 99 ranger 2wd, 3.0 v6. The ignition key lock cylinder broke in my truck the other day, I removed the cylinder but had a little trouble getting the part of the cylinder that broke, out. I had to remove the green plastic piece and the metal piece beneath that. When I tried putting them back in, the metal piece is in fine but when I try to turn the ignition with a screwdriver(just to make sure it is turning correctly, not to start the truck, battery is disconnected) the green piece doesn't turn with it, it pops out. A few questions, What is that green piece and what does it do? I was told that the steering wheel could lock up on me if it wasn't in correctly, is that true? Is that green piece supposed to move with the turn of the key or does it stay stationary? Any help would be greatly appreciated. Thanks