I have a Qt based tool and I want to add a QtWidget(button) in the gui which will act as a help button for my tool just like the windows help button for any application. The help button when pressed should display some text information in the form of list of points and each point could be further expanded . how do i do this? can I use the QDialogButton for the same?

Well, you could attach a signal to the button, so that when it's pushed it will perform some actions, in your case to show the help. It's been a while since I've worked with QT so I don't have a concrete example (not a correct one at least), so I'll link you the official documentation. Qt signal and slots

For help viewers, you should use Qt Assistant help-files, which are the Qt equivalent of Windows help files / menus. The Qt Assistant framework has all the features you are describing, and the help files are easily generated from html pages. With that, it's just a matter of launching it upon the OnClick signal of a button (don't use "QDialogButton", that's for buttons that are inside a QDialog, such as OK/Cancel buttons). You can check out this tutorial about integrating Qt Assistant in a Qt application.