Data retrieval project using JavaScript and XHR - repost

I find myself building a CMS-based site for a client who requires securities data retrieval from a related site. The related site has provided brief details of how to retrieve various types of information information from their server using XHR. I need working examples based on this code which can be implemented using HTMl/XHTML, JavaScript and (if necessary) PHP. The code supplied passes various parameters in the URL to provide data on a particular security. Different pieces of data are loaded using JSON. I suspect this task is relatively simple for a programmer with an understanding of Web applications, but it is beyond my capability.