Hi and welcome to the forums!
I wrote an article for Adobe's Developer Network which you may find helpful on how to implement context sensitive help with a web application using the WebHelp API. It was written for an older version of RoboHelp, but the concepts are virtually the same.
In additional you will find more information regarding application help from these two resources. Some of what you need will depend on the language and platform of the application (.NET, C++, C#, PHP, Java, etc.) These are covered in the documentation:
This is the online help topic for context sensitive help on Adobe's website.
Calling WebHelp on Peter Grainge's site
In addition, if your developers are using C++ language to develop their applications, you may find a new automatic feature in Adobe RoboHelp 9 to be useful.
You can download a trial version to check it out here:
Adobe Certified RoboHelp and Captivate Instructor