The right hand door is the first door you open, swivel the custom catches up, there’s one on each handle.
You’ll notice that your container is fitted with lock rods which run all the way from the bottom of the doors through to the top. At each end of the lock rod is a cam and a keeper which engage to allow the door to lock.
Lift up the door handles and twist slightly to make sure the cams and keepers are dis-engaged.
Next take hold of the inner door handle first and pull out slightly followed by the outer handle and then pull them in tandem.
Closing the doors is just a reverse process of course, start with the left hand door, engage the cams and keepers and then twist both handles. Finally swivel the custom catches down.
And that’s how you open and close a shipping container door!