Firebase Firestore Integration

I need help connecting my partially built app to a Firestore database on Firebase. The primary function I need is data storage and retrieval.

Requirements:
- Set up Firestore database from scratch
- Connect the existing app to Firestore
- Ensure smooth data storage and retrieval

Ideal Skills and Experience:
- Proficiency in Firebase and Firestore
- Experience with app integration
- Strong background in database setup and management