Player 2 : Once player 1 is finished, fire your portals on the ground panel and the vertical wall panel to your right (it overlooks the platform where the exit door is).
Player 2 : Fall through and join player 1 at the exit to the first half of this test chamber.
Player 2 : Once player 1 is up here, you need to replace the portal below with one of your own and then set an exit portal on the vertical wall panel to your upper-right.
Player 1 : Drop down and you'll fly across to the ledge with the red switch. Walk over to it and stand on it whilst you wait for player 2 to complete their next task.