I need to wire up a solenoid to lawn mower

If this is for starting, Large battery cable to 1 of the large post of solenoid
A large wire from other large post to Starter, Then you need a Ground to one side of the Solenoid, coil and may want to go through any safetys.
Tehn the other side of the soil connects to the Start wire from ignition switch, can also be just a pushbutton switch to engage Starter.