The compiler help file is a true Win32 help file. To open the compiler help file, use Winhlp32.exe. The winhlp32.exe program resides either in the Windows directory (usually C:\windows, C:\win95 or C:\winnt) or in its system ( Win32s) or system32 (Windows 2000, Windows XP, or Windows Vista operating systems) subdirectory. The Win32s distribution also contains Winhlp32.exe.
To change the association with Windows 95 or Windows NT either (1) use the explorer menu View > Options and then the File Types tab or (2) select any help file and press the Shift key. Hold it while opening the context menu by clicking on the right mouse button. Select Open with from the menu. Enable the Always using this program checkbox and use the Other option to select the winhlp32.exe file.