Partial Answer
The first step is to solve the "magic eye / autostereogram puzzle". By crossing your eyes and moving the picture back and forth, an image should float up.
Not sure what to do after that, though. I can't really think of a way to describe the "technique" used to "see" an autostereogram, nor do I understand what the solved autostereogram is referring to. If I assume that "I" refers to the autostereogram itself, but there are many,still many dates involved in the history and creation of autostereograms.
