i am trying to learn springboot myself from free resources and reached to the curd operation program and i am got 404 error when i try to post request [closed]

this is my controller class

this is my service class

this is the repository interface

this is student class

the database is created successfully in mysql but when i try to post the data from the postman i am getting 404 error i don't understand why

this is the error i am getting in the poatman

i want some help from experience people beacuse this is getting late when i try to find answers myself and this is my first question so I don't no how i explain my question so understand my problem and help me