The “black window latch” is referring to the bracket holding the red handle in place. Disengage the red handle, straighten the handle rod until it is 90* to window, push outward and engage notch in red handle in edge of window to hold it open if just getting ventilation. Push all the way out if egressing trailer. To retract, lift slightly on handle to disengage from notch, close window, and return red handle to bracket