Discovery 6

Once the Shuttle gets real close, it's docking assembly is extended a bit and slides into the ISS dock, where it is hooked by grapple hooks and screws. When everything is set, the docks screw themselves together ( called mating) and at last you have a hard dock. They will go through over an hour testing the airlock and seals before the hatches are opened and allow the shuttle crew into the ISS.