Making a call from one website to another (form related)

[eSDee]

I am trying to figure out a way to calculate a total on one webpage, and then send that total to another page for processing. I was told by the programmer of the second page to make a call to his page and include the total. I think I understand what that means but I have never done it before. Is that just like naming a form field, then in the submission process sending the variable to the page where you are redirecting to? I know this is pretty random and nobody might be able to help me but I thought it was worth a shot.

Thanks friends.