Add your engine's Public path to your compiler include path, so that the IDE knows where to find UE header files.

Where did you install the engine? Ex:

```
E:\Program Files\Epic Games\UE_4.26\
```

Then (assuming you're using Visual Studio Code, as recommended in the Udemy tutorial) go to:
View / Command Palette / "C/C++: Edit Configurations(UI)"

Scroll down to "Include path" and, if missing, add your UE Public folder, ex:
`E:\Program Files\Epic Games\UE_4.26\Engine\Source\Runtime\Core\Public`

Intellisense should now know where to find CoreMinimal.h

You may have to close and re-open your .cpp file to trigger the modified Intellisense path.

Also note that as of this posting 5/6/2021 Intellisense will continue to have difficulty loading CoreMinimal.h because of a separate and unrelated problem relating to macro expansion. You may see:


> cannot open source file "UBT_COMPILED_PLATFORM/UBT_COMPILED_PLATFORMPlatformCompilerPreSetup.h" (dependency of "CoreMinimal.h")


So while CoreMinimal.h will still appear red-underlined, the reason is different now.  That's progress!