Consuming the REST API from .net


I have a hosted instance of Discourse and want to add users via the C# web api we are using in our visual studio project.
Our architecture uses a Sql server back-end with Web Api and Angular at the front-end.
Our users fill in a form on our site and we need to be able to programatically add them the forum so we can then provide them with a link in subsequent pages.
What is the best approach to doing this?