think of it as a bar that is left to right. you use your mouse to "target" the opening.
[ - - - - - - - - - -] (i imagine 10 spots myself, like this example.)
this bar has one point that lets you open it.
the points next to it let you attempt to open it.
[ 0 0 0 0 1 1 2 2 3 2 ] for this example #3 opens the box.
#3 opens the box, #2 attempts to open the box and usually makes it look like you are super close. #1 you'll get a slight swivel to the lock but nothing more. #0 you get a jiggle and nothing more.
so in order to unlock it you have to imagine moving your mouse through this bar to get where it unlocks.
[ 0 0 0 0 1 1 2 2 3 2 ]
↑ ( mouse pointer on the imaginary bar.)
__________________
Hope this helps.
games that have similar lock-picking that i know of: the elder scrolls.