Help using REST API, Error: Not Permitted

Hi All,
I’m trying to insert records in custom doctype. Things I have tried till now are:
In app’s api.py added,
@frappe.whitelist()
def insert_opp(id,name):
session = FrappeClient(“http://localhost”, “username”, “pwd”)
doc = {“doctype”:“docname”,“rfq_id”:id,“opportunity_name”:name}
session.insert(doc)
When I pass this in POSTMAN or browser error “Not Permitted, You do not have enough permissions to complete the action”

Please help me resolve this

Refer this,

https://frappe.io/docs/user/en/guides/integration/rest_api

Thanks Sangram.