This tutorial guides users through the process of uploading an audio file from their local machine to the AssemblyAI Speech-to-Text API and submitting that audio file for transcription using C#. The procedure involves interacting with three separate AssemblyAI API endpoints: Upload file, Submit for transcription, and Get transcription. Pre-requisites include .NET 5 SDK, Visual Studio 2019 Community Edition or above, and an AssemblyAI API key. The tutorial also provides detailed steps on how to get an API key from AssemblyAI.