software – What is the process of adding a new feature into an application

Fake scenario

I have an existing library application where users can hold books , block it for reading. Every user has a library card with card with number.

The business team asked me to work on a new feature to add where a user can change his or her name twice a month and we will mail the card to them. We have to just let them do it twice and not more than that due to cost reason.

What would be the process of bringing this feature developing it and rolling it out.

As a development manager what steps do I need to take