Where can I find the data on different components, like mosfet enhance n channel. If I use a mosfet enhance n channel transistor with a threshold voltage of 14V will it turn on at 14V if so what voltage will it turn off,? 13V
FET threshold voltage is the voltage where it has barely started to conduct. You won't be able to find a FET or other component that turns fully on at 14V and fully off at 13V, you need much more than that, a complete circuit with lots of components.
In general you pick a component and it will have a datasheet. Or you can search for components given some parameters like maximum current or on resistance.