How do you make classes in JavaScript?

How do you guys make "classes" in JavaScript!?

I am using:

function classFoo()
{
   var classLevelVariable = 0;

   this.classFunction = function()
   {
      alert("The classFunction has been called.");
      classFunction2(); //Crash.  classFunction2 is "undefined."  
   }

   this.classFunction2 = function()
   {
      alert("classFunction2 called.");
   }
}

I never was able to get constructors to work. Tried

this.New = function(arguments)

Which worked once, but not in a second class. So, I have now given up on those entirely, using my own "Initialize" functions which act as constructors.

The weirdness with it working once, but not twice, makes me think typographical errors between the two classes... but I think in 19 years of coding, that that probably isn't it.

I'm using Chrome's debugger, and I am not receiving any errors besides the second function being undefined when being called.