I think what he is having trouble with, is getting the game to read a json or xml file from an external server(url). An issue I was having as well at one point. By default, browsers are set to block those request, so you have to give that permission manually.
I think this is what your after? Copied from tutorial.
Making AJAX requests cross-domain or in preview
By default, browsers block AJAX requests across domains. This means, for example, a game on scirra.com can request other pages on scirra.com, but cannot request pages on facebook.com. This is an important security feature of web browsers (it is not specific to Construct 2 or its AJAX object).
Also, when previewing in Construct 2 the game runs on localhost. This counts as a different domain to the rest of the internet, so typically AJAX requests to any web page will fail during preview, unless the server explicitly allows cross-domain requests.
*** (this part is the trouble. Lack of explanation here down)****
If you want AJAX requests to your server to work from any domain, or in preview, you can configure it to send the following HTTP header:
This will enable AJAX requests from any domain, but you should still be aware of the possible security implications of this. For more information on cross-domain requests see HTTP access control on MDN.