Sometimes it's the little things that present mind boggling puzzles. For me, it was spending an hour trying to reattach a glove compartment door!
OK; take your spring. One end of it has a closed loop; the other end has two arms which stick out in opposite directions. The overall shape of the spring is like a letter "C" . With the open end of the spring facing up and the engine cover in its normal orientation, squeeze the two arms of the spring together and snap the spring arms into the two holes on the spring holder of the engine cover. Mount the two engine cover hinges onto the body of the car. Have a buddy hold the engine cover in hover mode while you take the closed loop end of the spring and hang it into the roughly "C" shaped spring holder which is up under the lip of the engine compartment. It just inserts into the opening. At this point there is no tension on the spring. Attach all of the hinge bolts just snug. With the spring mounted in this position it will build torsion as you close the engine lid. This stored energy opens the lid. You may have to adjust the position of the hinges to get a correct fit and to make the latch work. Hope that this helps you. Dan (MY72BUG) in Goderich.
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.