You just push the pin in with the chain-break as others have explained above. Line it up with the pin on the tool and push it in. A chain press pushes two pins on one side of the master link into the plate on the other side. Lookup motorcycle master link and you'll see what I mean. By the way, track sprinters use quick links so I wouldn't be too concerned about their integrity on your coaster brake bike if you decide to go that route. All of my bike chains have quick links.