Hello digger. You need to be more specific when posting, i.e., which console/pc, which game you're playing, the level you're in.
However, I do know that you're on SC1 (Stealth Action Redefined) and on the Police Station mission, looking for Blaustein's Black Box.
You've obviously made it through the flaming buildings and smoke filled room to the checkpoint where you've got an alley below you with several men patrolling. To get to the black box, head to your right until you find an opening, jump across (only when the men below won't spot you) and follow the path to a porch/balcony where a guard is on his cell phone. Make your way through the hall in the apartment to the last one on the right. The black box is behind a picture in this bedroom...
And to help you where i got stuck. The code to the door is in your OPSAT after you've found the black box. But to get there follow WarriorOfLights helpful instructions.
No worry's. Man...i wish i was in your position having not played a splinter cell game before. You still got the rest of this game to go then another 3 after that if you continue on of course. I loved it so much when i first played it lol.