Microsoft Learn following instructions causes error

Hello in the section Create and run simple C# console applications (Get started with C#, Part 2) / Install and configure Visual Studio Code for C# development, Unit 7 out of 9
it says to type dotnet build into the visual studio terminal, but when I did so it gave the error:
MSBUILD : error MSB1003: Specify a project or solution file. The current working directory does not contain a project or solution file.
What do I do?

is your terminal in the folder with the file you want to build? if not, move to that folder. Or verify that you have saved the file in the right place