Just like everything else in the game, fry cry highlights everything that's objective related.
There is a red meter on the top of your screen that shows your progress. Go through each room and take out all computers, stamping machines, boxes of posters, Transportation vehicles, and most importantly the power generator.
Power generators needs to be taken out using C4 or explosives of some kind. After all this is finished, you'll get a few more waves of men, take them out. And that should complete the mission.