If you want to dive right in, the implementation of the Uber H3 API in h3net can be found at Uber H3 API.
Or, you can read the auto generated docs and work out how the internals work, though that's subject to change before release.
While this is still being built, I'm running an auto build of documentation. Later, I'll clean it up, but this will give you an idea as to where it's at, at any given moment.
Currently, this is using XML-Documentation that gets turned into one big XML file, then it's auto converted to a MarkDown file via lijunle/Vsxmd
Later in the project, I'll start editing the structure of that into bite sized chunks.