Remove the cable from the rudder and pivot point. Maybe spray with WD 40 first. Remove nut holding it on steering wheel cable, Depends on model boat. Pull old cable out of run but attach new cable at end WITH tie raps,,,,
Note the direction you turn steering wheel to unload inside cable.
INstall at rudder end...
Install at steering wheel secure nut. turn wheel and test that you have full rudder turn.
WHERE DID THE CABLE BREAK..?