ERPNext Custom Integration

Hello !
I am trying to integrate erpnext with the my own marketplace like there are integration available for shopify and other products but i want to integrate it with my own product like if someone makes any order or any changes i want that will sync into my erpnext as well for that what procedure i need to follow or how can i achieve that ?
Any idea or any suggestion will be very helpful.
Thanks so much in advance.