Place the two halves together, to get the proper alignment. Mark the screw hole positions lightly.
However, you do not want to use the bottom set of those markings. Instead, you want to mark something like
3mm below those markings... as you want the spring tension to take place.
If you place them too close, the spring wont even activate, or it will barely be any resistance.
If too far apart, it may be too tight. Too hard to snap shut and open... if you can even get it to
close.
Best thing to do, is to try it on scrap wood first. Then, when you finally get the proper distancing
for the correct tension desired, measure and copy that to your work-piece.
You do NOT bend the spring manually! The tension is created from the proper spacing.
Look at the side of the thing. There is a slide that allows the spring to travel
backwards as its being clamped. You can get a good idea of the springs
travel distance from looking at that.