Locking from Inside 

1. Turn the lever to the left (horizontally) 
2. Shut the door with medium force. (Seal on the door prevents it from lining up if closed too softly)
3.  Lift up on the handle to engage (you will hear it.)
4.  Pushing down on the handle from the inside will unlock the door. 

Locking from Outside 

1.  Shut the door with medium force. (Seal on the door prevents it from lining up if closed too softly) 
2. Turn key to the right 
3. Lift handle to engage 
4. Remove key