First of all, as with fitting all new or used car parts, Always remember safety! If you raise the vehicle on a jack Always support the car with axle stands! The one thing to be careful about when removing the wires to the starter. There is a red wire fitted from the battery to the rear of the solonoid, this wire is live & if it comes into contact with anything which is earthed, you will have problems. So be careful, a good rule of thumb is to tape up any wire ends with electricians tape or disconnect the battery completely but only if you have your radio code.
The two lower starter motor bolts are best accessed from the underside of the vehicle as these two lower bolts are located on the underneath of the starter motor. You will find the starter motor located in the centre of the engine at the rear under the air filter box and above the exhaust front pipe. The starter is connected to the car battery with red wire you must disconnect this wire by undoing the 13mm nut and washer from the rear of the starter solonoid, then you will find a 10mm nut and washer securing the wires on the smaller terminal. After removing the wires from the rear of the starter solonoid you will then need to loosen the two 13mm bolts that secure the starter motor to the gearbox. (A good tip is to always remove the lower bolts first to save the weight of the starter pulling downwards with gravity making the top bolt appear tight to the very last thread)
The lower bolt can be easily located and undone from the underside of the car where the top bolt is not quite as accessible, the top 13mm bolt is best accessed from under the bonnet at the rear of and below the vehicle battery it is easier to access this bolt with a 13mm socket.
To refit your new or used starter is a simple reversal of the removal procedure. After finally reconnecting the vehicle battery the starter fitting is complete. Finally expect to pay around £25 for a good second hand used unit from a Car Breakers Yard.