how do you replace the solenoid

the starter one i think its by the battery but im not sure

To find the starter solenoid just follow the large + cable from the battery it will go to the solenoid. To replace it remove the neg battery cable, remove all cables and wires from solenoid noting where they go back to. remove solenoid from it's mount. reverse order to replace. If the starter is for some reason mounted to the starter replacing the whole starter is the best choice.