A solid, wooden gate blocks the exit. So move to the left side of the room.

Shoot a rope arrow into the dangling bell.

When Lara pulls it toward the middle of the room...

...the wind causes it to crash through the wall, making an opening so you can get out.

In the next room, move to the left and take a running jump up little ramp and across the gap to grab the ladder made of planks. Climb onto the ledge above.

Move close to the anchor post on your right.

Turn around and shoot a rope arrow into the bell hanging from the ceiling.

As you zip up the line...

...the rope supporting the bell snaps, and Lara starts to fall.

As she grabs onto a wooden beam, press Interact to keep her from slipping.

Then pull up onto the beam and walk up it to the other end.

It tilts downward as you go but doesn't break. When you reach the end of the beam, turn left and jump to grab the next ledge.