Hi - assuming you mean 'Solenoid' ;-
1) Locate it - it's a device located between the battery and the starter, and could be anywhere on the tractor - different manufacturers have chosen some really imaginative locations over the years. Follow the heavy wire from the battery positive terminal. The first device in the line will be the solenoid.
2) Unbolt the connections and replace it. It's really that simple, it's only access to it that will give you any problems. Craftsman usually put it behind the fuel tank.
phil_saunders@bigfoot.com
Phil Saunders
June 2008