No, I'm sorry. Actually I haven't really checked out the AJAX feature in Construct 2. But as I'm a freelance web developer I've used AJAX an PHP together in many website project.
Do you have any earlier experience in web development using Javascript or PHP? If not you might want to learn the basics of those languages before moving on to implement it in your game.
EDIT: I just noticed that the AJAX feature in Construct 2 seem to be focused only for retrieving content and not passing variables. So I might have been wrong in what I told you earlier.
But the best idea is to wait and see if someone else answers I think. I just began using Construct 2 so I haven't really got very big knowledge about the plugins available and such.