To sort out the clues

get out and follow your teammate, meet up with friendly forces and listen to his briefing on the situation, the mission is to rescue the marines. Move with the squad, walk through a school to the street, then split up in teams of two and meet up in a car park. When you get to the car park your teammate is wounded by a sniper from a distance, follow the on-screen button prompts to drag him back behind the bunker in the room and then take out the enemy outside.