When that happened to me the first time, I felt pretty much the same way.
First off, make sure the coil is not all wrapped up within itself, but free of itself. ( I know, terrible description, but I think you know what I mean)
Second, you'll see the end with the hair pin bent end on it. The plastic wheel thing has got a slot on the outside of it and that bent end hugs the LEFT one.
So looking down at the plastic wheel, that slot looks sort of like this: ----_____----
The LEFT one is the one you want. Stick that end over the plastic end, keep a finger on it, and press that coil around the wheel. It's kind of tricky until you get used to it, but go slow, continue to keep that coil pressed down as you insert it back in. If you let go of it at any time, or if your pressing technique slips, you'll be starting over, because that spring will go "Boing", again.
You'll continue to wind it back in, within itself until you get to the end. Once it is nestled inside the wheel, your done but still be careful of it.
Once that is done, you'll have to eye up that pin on the case to the position of the loop in the coil. At this point, you wind your rope up on the wheel (Counter-clockwise, I'm pretty sure), and you carefully drop the wheel into place. Here you should test it to make sure it works right and spins with the tension in the right direction.
Before I go on here, if you need to replace the rope, it's best to do that before you wind the coil. As you will see, the knot for that rope is in a cavity that is situated under where the coil is going to be. When replacing the rope, push it through that hole, tie the knot, and get that knot crammed in there as much as possible.....what ever is exposed above the level of that cavity, the coil will "grind" off over time.
Once everything is in place, you will need needle nose pliers or something like them to grab the end of that rope-end to slide it through the rope guide.
You may want to give that wheel a few turns to put some tension on it, which will add to the return from a pull.
Getting the rope end through that hole (the rope guide) is a little tricky with the tension, because it will want to pull it back, but you will get it. Winding the spring is the hard part, if your not used to it!
Hope this helps.