Both Visual Studio Help formats – Help 2.0/HXS and Help 3.0/MSHC – are irrelevant for normal help and documentation purposes. You cannot view or use them unless you have the Visual Studio .NET programming package installed and you cannot even create Visual Studio 2008 without Visual Studio. You cannot use Visual Studio Help to document normal application programs.
Surprisingly for a help format that was touted as the best thing since sliced bread, the features and capabilities of both the Visual Studio Help formats are actually considerably more limited than those of either the obsolete Winhelp format or HTML Help, the formats both versions of VS Help were originally supposed to replace.
Many common features of Microsoft's earlier help formats are not available in Visual Studio Help. For example, window types are not supported at all, nor are links to external files. Links to external videos are also taboo in Visual Studio Help. The only external links that are permitted are web URLs with absolute addresses.
To publish Help 2.0 you need Visual Studio 2002 or later and the Visual Studio Help Integration Kit (VSHIK), which can be downloaded from the Microsoft website (check the MSDN site for details). Both these packages must be installed to publish Help 2.0 with Help+Manual.
After installing the Help 2.0 compiler go to View > Program Options > Compilers in Help+Manual and make sure that the correct path is entered to the compiler executable.
To view Help 2.0 documentation you only need Microsoft Visual Studio 2002 or later, the VSHIK does not have to be installed. Unlike HTML Help there is no stand-alone version of the Help 2.0 viewer. If you don't have MS Visual Studio installed you can't view Help 2.0.
The MS Help 2.0 compiler:
The MS Help 2.0 compiler is part of the Visual Studio Help Integration Kit (VSHIK), which you must download from the Microsoft website in the correct version for your version of Visual Studio .NET. Unlike the HTML Help and Winhelp compilers it is not a stand-alone compiler system. It can only be used in combination with Visual Studio .NET, which you will have if you are programming Visual Studio .NET components. If you are not programming Visual Studio .NET components you don't need it. Got it?
The Visual Studio Help Integration Kit:
This package is available directly from the Microsoft website. Unfortunately, the download location has been changing quite frequently recently so you will need to search for it on the MSDN site yourself – any download link we could provide here would probably be obsolete again by the time you read this.
Unlike Visual Studio Help 2008, the new MS Help 3.0/MSHC format does not require a special compiler. It is really just a zip archive with the extension .mshc, containing XHTML topic files and configuration files. Help+Manual can generate MSHC files directly without any assistance from other software.
There is also no special viewer for Help 3.0, although Rob Chandler has produced a very nice one. The default viewer for MSHC help files is your default browser, but this only works if Visual Studio 2010 is installed, because it provides the necessary software for making the help contents available to the browser.
Visual Studio Help (Reference)