You'll need to find this column next, it's the only way you can go up for now.
Use the cracks to go higher.
Jump towards the nearby column, Lara will grab onto one of those ledges.
And you're finally back up.
Ok, the first part wasn't so necessary, but it's a good exercise and it helps you learn the area better, you do need it quite a bit. The next part is important though, and you can do it the first time you enter the area.
You need to start at the point just right to the entrance.
First, do a running jump to the thin pole, swing across and use the grapple to do a wall run. When you get to the end, position towards the rock on the left and jump to it. You'll also find some ammo there.
Do a running jump to the ledge up ahead and then to the other ledge.
Use the grapple once more and you've made it to the other side.
That hole is a quite big, so make sure you stick to the wall and do a long jump (hold Jump longer).
Don't get fooled by the lighting and jump over the next holes.
And in the end you finally reached the first box. Push it.