The first chapter serves as a sort of tutorial, but it isn't a total walk in the park. After you gain control of Hayden, continue on down the stairs. Leap over the wall and jump through the window. Smash open the box of ammo on the right and shoot the lock off the door. In the room with the slideshow about Enferon, plant a C4 charge on the second pillar on the right and continue through the doors ahead.