Unable to run deepstream 7.1 using custom model

Please provide complete information as applicable to your setup.

• Hardware Platform (Jetson / GPU) Nvidia geforce rtx 3090
• DeepStream Version 7.1
**• NVIDIA GPU Driver Version (valid for GPU only)**560.35.03
when i am running the deepstream _test_3.py for multistream using custom model i am getting the following error. Kindly help me understand the step by step procedures to run deepstream using any custom models.

ERROR: …/nvdsinfer/nvdsinfer_func_utils.cpp:31 Could not open lib: /usr/lib/libnvdsinfer_custom_impl_Yolo.so, error string: /usr/lib/libnvdsinfer_custom_impl_Yolo.so: cannot open shared object file: No such file or directory
0:00:01.674210931 30 0x5b6e57d539b0 ERROR nvinfer gstnvinfer.cpp:678:gst_nvinfer_logger: NvDsInferContext[UID 1]: Error in NvDsInferContextImpl::initialize() <nvdsinfer_context_impl.cpp:1342> [UID = 1]: Could not open custom lib: (null)
0:00:01.674230415 30 0x5b6e57d539b0 WARN nvinfer gstnvinfer.cpp:914:gst_nvinfer_start: error: Failed to create NvDsInferContext instance
0:00:01.674234872 30 0x5b6e57d539b0 WARN nvinfer gstnvinfer.cpp:914:gst_nvinfer_start: error: Config file path: custom_model_pgie_config.txt, NvDsInfer Error: NVDSINFER_CUSTOM_LIB_FAILED
Error: gst-resource-error-quark: Failed to create NvDsInferContext instance (1): gstnvinfer.cpp(914): gst_nvinfer_start (): /GstPipeline:pipeline0/GstNvInfer:primary-inference:
Config file path: custom_model_pgie_config.txt, NvDsInfer Error: NVDSINFER_CUSTOM_LIB_FAILED

Please refer to the following document about nvinfer configuration file and correct the errors in the configuration file.

https://docs.nvidia.com/metropolis/deepstream/dev-guide/text/DS_plugin_gst-nvinfer.html#gst-nvinfer-file-configuration-specifications