If you're looking for a solid blog post on the Steam 64 API DLL, I can suggest a few topics that might be covered:
You should only attempt this if you already have the file on your system but Windows can’t see it.
The Steam API is a set of libraries and tools provided by Valve Corporation that allows developers to integrate Steam functionality into their games and applications. The API provides a range of features, including user authentication, game tracking, and community features.