i have read How to generate C# documentation to a CHM or HTML file?. but, i use visual studio 2012 and all of the answer to that question is in visual studio 2010 and lower. so, how i generate it in visual studio 2012?
Sandcastle Help File Builder is my favourite..
You simply code as normal and it generates itself.
There is a getting started tutorial here:
http://www.ewoodruff.us/shfbdocs/Index.aspx?topic=html/b772e00e-1705-4062-adb6-774826ce6700.htm