The attached is my .CHM recompilation of the old .HLP manual that came to me in a freeware MASM32 distro some 10 years ago. The old Windows Help format is no longer supported on Vista+ platforms but this recompilation will solve this issue for you.
The manual dates back to the times of Windows 95 and NT but 99.9% of its data is relevant to, and usable under, the Windows operating systems of today. It is in fact a micro-MSDN on your desktop -- a must-have for the Win32 programmer.
Be sure to read the introductory chapter in order to be able to find your way around and get the maximum information available in the manual.
[UPDATE] With the help of Marc Pons, a BASIC enthusiast and active member of FreeBASIC community, the Win32.chm file now has its functionality restored in full. The overall file size has also been reduced to under 6.7MB by recompilation in the authentic MS HTML Help Workshop editor.
Please re-download and enjoy this instrument in your professional and hobby programming.