I need help with error in visual studio. New to All of this

I am working my way through the C# and every time I try to run the program in visual studio code I get a error saying the file is not found. I tried on two different laptops one running Linux mint, and the other is a Windows PC and I’m getting the same error on both. Is it something as simple as creating a new folder the project did I do something wrong when creating a new file

How are you running it?