I am a post-non player but thought buying the first splinter cell game for my pc would be fun. and now I'm already stuck on Blausteins apt. After I open the door from the burning building to find the "black box", i cant seem to get from off the ledge or open anything or jump onto anything. I also tried shooting out all the lights adn sneeking around. WHERE DO I GOOOO?

You've got to follow the balcony all the way to the end. Right before it dead-ends, on the right there is an open ledge that drops down to the street. Get a running start if you can and jump the ledge; you should grab the edge of the other ledge across the street.