Add two numbers (with JavaScript)

Here we go list:

I am learning JS by using the "trial and error" technique.  Just a book and my
friends on the list.

I need to check if the sum of two fields is greater than a third field.  If that
is true, I have to send a message (alert).

The form name is "Joboff" and I want to be able to do something like this:

  if (TOTAL > Joboff.opropn.value)
  {
    alert("The combination of good quantity and scrap is greater than the open
quantity");
    Joboff.rsn.focus();
    return (false);
  }

The variable TOTAL should be the combination of the two and
"Joboff.opropn.value" is the value to be compared to.

What I should do?

TIA,
Peter Vidal
Pall Aeropower Corp.
SR Programmer Analyst
WWW.Pall.com / 727-539-8448, x2414

"A good player makes himself look good; a great player makes the team look
good."
Author unknown