Yeah, you only need to sit behind one specific computer - it's highlighted by the ceiling light. I planned to make the other PCs usable too, but only as simple computers without the police software. Basically, in this game you have to connect to other PCs after an NPC sits down at them, spy on their activity, and check their files with the "Cyber" software. Red files are important, but only the ones with the right theme/tags. So if you're looking for a hacker, the files should be related to things like "remote_control", "hacked_something", etc. After finding 3 out of 5 files like that, you can arrest the suspect.
You can also check who is currently downloading those files through the webcam. That's pretty much it. My original idea was much bigger and clearer, but this was only my second 3D game, so it was hard to finish everything properly. But you definitely can win, I do it all the time.