If you want to use separate accounts, she will need her own account. This document explains how to create a new Apple ID (create an Apple Account) --> How to create a new Apple ID - Apple Support
If you wish to use different accounts with one subscription you will need to set up Family Sharing as outlined in this article: Set up Family Sharing - Apple Support You could, of course, each just have your own subscription.
This article describes how you change the settings on an Apple TV to provide for different user profiles:
Share Apple TV with multiple users - Apple Support