High School Diploma Certificate from New York (Santiago de Chile)

Hey guys; if anyone has experience with this please help. I need to get a legal copy of my High School diploma from New York (Long Beach High School). I´ve been told I need to get a sealed envelope from the H.S and get it stamped by the Chilean Consulate in New York. However, I´ve been also told that, apart from the Chilean Consulate, I need to take them to two other places in New York. Has anyone done this procedure and can clarify it a bit for me?
Thanks in advance.