Glad that you get that one fixed. I would assume that there was some type of error when creating the project on VS which didn't end up having the file for reason or another. If you keep seeing that in the future, please let us know. Also, welcome to the community.
Since you are new to our API/Platform, there definitely will be a lot to look into. Here is some inspiration
Get Started with Example Apps | ArcGIS for Developers is a page where you can find our examples, which in this context means apps that are built to demonstrate how to solve some use cases with a "fully working open-source app". These are intended to highlight good practices and showing how to tie multiple functional areas to a single application.
GitHub - Esri/arcgis-runtime-demos-dotnet: Demo applications provided by the ArcGIS Runtime SDK for ... is a repository where you can find all kind of demos. Where example apps are built around use-cases, demos are more API functionality based. Quite a few of these are used in our presentations as demos.
GitHub - Esri/arcgis-runtime-samples-dotnet: Sample code for ArcGIS Runtime SDK for .NET – UWP, WPF,... is a repository where you can find samples to highlight specific API usage.
One relatively new page is to look to Browse ArcGIS DevLabs | ArcGIS for Developers which contains short labs that you can do to learn specific things and you can chain some of them together as well. This is quite nifty so I recommend for you to have a look.
Ofc then we have the guide that you are already looking into. All the feedback is more than welcome. We are trying to make the process of learning our API/Platform easy as possible but there are a lot of things to show. So please let us know how you find the learning process.