Here is a simple step-by-step tutorial to installation and configuration of Open CV with C++ and Visual Studio 15.
This installation guide is bas(ically identical to)ed on this guide found online: https://www.deciphertechnic.com/install-opencv-with-visual-studio/
1) Install Visual Studio 15
From this page. Download the excution file and run it. The installer is self-explaining, just keep the express settings, pressing "next" all the time.
2) Install OpenCV