How do I add PublicAdditionalLibraries?

I’m following this tutorial by Rama to link a library:

When I get to step 2, I cannot find a build.cs file. I have MyGame.Target.cs and MyGameEditor.Target.cs, so I’m not surprised that trying to add the next line of code didn’t work. I get this error:

The name ‘PublicAdditionalLibraries’
does not exist in the current context

I also added using System.IO as per another tutorial. What is the updated way of adding PublicAdditionalLibraries? Thanks.

Oops, I actually did have build.cs in the source directory.