If you are using Help Workshop, that is where you should edit the .cnt file. As for the .rtf file, Office (Word) will do it up reasonably well, with service pack 2. To attach the help file to your program, if it is VFP, simply go to the App builder and put the path to the help file in the help directory edit region.
It has been a long time scince I did one in C++, but it is not that much harder.