The setting of the first two lasers is visible in the screenshots below:
In the next section of this location, each switch is connected with a wire to one of the track. Please move them in such order, that only the blue beam shines into the beacon.
Then proceed using the handle above the beacon on the left side to open the first gate, clear the tiles in then newly opened room and shine a green beam into the second beacon
Use the handle above the second beacon to open the next room and clear it, so the beam can shine through the room
On the last screenshot in this article, you can see a screenshot that shows, how to use the switches to complete the bridge.