EC Levels

Ok people, i am clued up quite a bit on growing and what to do have some good grow on here also but am setting up for a really big professional grow and the only thing i havent clocked yet or really have worried about is the EC readings.

I know what your all gonna think NoOb!!! but im not lol i promise.

ok here it is - i dont know how to take EC readings iv got a EC reader penin the psot how do i use it lol

PS: Dont laugh