Very simple deepstream nvdosd example? ( More simple than deepstream-app )

Hello,
I have looked at deepstream-apps that is included with the deepstream install. I have checked the guide for deepstream developers https://docs.nvidia.com/metropolis/deepstream/dev-guide/index.html. But I’m still not sure how deepstream works. Is there a step-by-step guide that explains how this project is put together?

My final goal is to draw shapes and text on the videostream (highlighting regions of interest with polygons, displaying of live data via rectangles that change colors). I do not necessarily need the deeplearning/AI feature.