Using my own data, how to make rpg_XXXX_XXXXXX.geojson for dataset_preparation? Thank you.

[soundandfree]

I use my own data, and generate a .geojson file based on polygon related to my data, but there is no 'ID_PARCEL' property in .geojson file. What is ID_PARCEL used for? How can I make my own geojson file?