Click one of your soldiers on the map, or his card on the left, or press keys 1 to 8.
Click anywhere on the map and he walks there. SNEAK is slow and quiet, MOVE is fast. Click a guard to mark him, then press SILENT SHOT or TAKEDOWN.
Time runs. The game pauses itself when a guard hears something, so you can re-plan. Press GO again to continue.
Red cones are what guards can see. Stay out of them. Not sure what to do? The green NEXT STEP bar at the top always suggests a good move: press DO IT and the captain gives that order for you.
Pick your eight-man SEAL team, plan every move while time is paused, then press GO. Silent sniper shots, takedowns from behind, cuff the target and reach the helicopter.