Calling the header file in the parent folder - c++

Question

I'm doing some experiments to learn CMake. So the commands stay in my mind. I created a project to test what I just learned. However, I have a problem.
The structure of my project is as follows:
├── bin
├── CMakeLists.txt
└── src
├── Configuration
│   ├── CMakeLists.txt
│   ├── Test
│   │   └── TestConfiguration.h
├── Array
│   └── Array.h
├── CMakeLists.txt
├── Test2
│   ├── CMakeLists.txt
│   ├── Test2.cpp
│   ├── Test2.h
│   └── Test2-1.h
├── Main
│   ├── CMakeLists.txt
│   ├── Config.h
│   └── Main.h
├── Test3
│   ├── CMakeLists.txt
│   ├── Time.h
│   ├── Timer 
│   │   ├── CMakeLists.txt
│   │   ├── Iterate.h
│   │   ├── Run.h
│   │   ├── Serial.cmpl.cpp
│   │   └── Serial.h
│   ├── Smart.h
│   ├── Counting.h
│   ├── Mute.h
│   └── MainTest.h
└── Utilities
├── CMakeLists.txt
├── Inform.h
├── Settings.h
├── Print.h
└── Const.h
But I didn't understand how I should make these CMakeLists.txt files. For example, the file src/Utilities/Inform.h uses the following header:
// src/Utilities/Inform.h
#include "Main/Config.h"
I've tried everything I've seen on the internet and stackoverflow to edit the src/Utilities/CMakeLists.txt file. But no matter what I do, it never sees the Main/Config.h file. I just need to do something like ../../Main/Config.h.
The same problem applies to other folders. What I want to learn here is to be able to navigate and call all files in the project with CMakeLists.txt. While doing this, I tried many of the following parameters:
add_library
target_include_directories
target_link_libraries
link_directories
link_libraries
I think there's something I'm missing or misunderstood. I would be glad if you help me in this regard. If you tell me how to edit the src/Utilities/CMakeLists.txt file, I will try to fill the others accordingly.
Additionally, there is something I'm curious about. Do I also need to edit the src/CMakeLists.txt file? Or is it enough if I just edit for example src/Utilities/CMakeLists.txt?
Also, I don't know if it will be needed additionally, but I'm using cmake version 3.16.3. My development environment is an x86_64 20.04.1 Ubuntu-based Elementary OS.
I've read the official documentation for CMake 3.16 and the answers from fellow developers on StackOverFlow. I want to use the header file in the parent folder in a header in subdirectories. But many ways I've tried are wrong. There is always an error in the include path I entered. I want to learn from experienced developers what I did wrong.