In this picture you see the Carriage/trolley connected to the opener. This is the normal operating position.
To Disconnect the Carriage/Trolley and operate the garage door manually:
Pull down on the cord and knob of the traveler Carriage/Trolley to release the door from the locking system. You can now operate your door by manually lifting and closing the door.
To Reconnect the Carriage/Trolley:
Pull emergency release cord and knob toward the door & up. Then manually lift or close the door until the inner slide & carriage/trolley locks into place. You should now be able to operate the door using the garage door opener.