I came across Intel's intro to x64 assembly when I was looking for some information on working with wide characters on 64bit (I seem to recall there were some new instructions introduced for that, I'm guessing one would probably be better off using libicu to parse eg: utf-8 into some form of 16-bit characters first, though?). Anyway, nothing on wide characters, but essentially a work-a-like hello-world for Microsoft Windows and MASM:
https://software.intel.com/en-us/articles/introduction-to-x6...