Basic understanding of of Dropbox API .NET

When you "create" a Dropbox API app on the Dropbox App Console, you're essentially just registering an app with us so that you can access the Dropbox API. Exactly where and how you write the code that does so is up to you, as is the UI for your app.

For instance, if you're writing a project in .NET (say, in Visual Studio), we recommend using the official Dropbox API v2 .NET SDK, as it will do much of the work of connecting to Dropbox for you. 

For instance, to create a folder, you would use the CreateFolderV2Async method, or to upload a file you can use the UploadAsync method.

To allow arbitrary end-users to connect their own Dropbox accounts to your app, you should implement the OAuth app authorization flow in your app. The .NET SDK offers a helper for that. I recommend checking out the included examples as a sample of how this works.