I need to create a webhook for salesforce in data insertion from external system(chargebee) for every event that occurs in chargebee that will hit the webhook URL to send notification in salesforce. any idea how to start on it...
IMHO you should hit the REST API in your webhook, sending the data that you need to insert to a customObject or whatever you need to upsert.
In addition, if you need to run any logic or convert your external data, you could use a trigger
before/after insert the object by REST API.
Take care with API governor limits.