The easiest way to handle a JSON response is to convert it into an object first. Then you can do a GlideRecord operation on a table and save that data there.

Here is a blog post that explains how to parse the JSON into a Javascript object. Then you can use that object in conjunction with GlideRecord:

http://www.john-james-andersen.com/blog/service-now/converting-a-json-string-to-an-object-in-servicenow.html