How start deepstream

Hardware Platform (Jetson Nano)
• DeepStream Version 5.0
• JetPack Version 4.5
• TensorRT Version 7.1
i would like to learn deepstream but haven’t found a good tutorial. I a fresh developer with nvidia tools but have some experience with deep learning. I would like count the number of orange in a farm orange to a proyect. Thanks

Please provide complete information as applicable to your setup.

• Hardware Platform (Jetson / GPU)
• DeepStream Version
• JetPack Version (valid for Jetson only)
• TensorRT Version
• NVIDIA GPU Driver Version (valid for GPU only)
• Issue Type( questions, new requirements, bugs)
• How to reproduce the issue ? (This is for bugs. Including which sample app is using, the configuration files content, the command line used and other details for reproducing)
• Requirement details( This is for new requirement. Including the module name-for which plugin or for which sample application, the function description)

We have quick start document, QuickStart Guide — DeepStream DeepStream Version: 5.0 documentation
you can start from here, then you can look into samples demonstrated for different purpose.
C/C++ Sample Apps Source Details — DeepStream DeepStream Version: 5.0 documentation
for how nvidia plugins working you can see,
GStreamer Plugin Overview — DeepStream DeepStream Version: 5.0 documentation,
about your case, you should have your models to detect or classify objects, for how to count the objects, you can refer to sample test1 function osd_sink_pad_buffer_probe