Create Item 
The Create Item method enables you to add a document to a collection in your Firebase Cloud Firestore.
To create a request to add a document to a collection, follow the steps below:
- Open the request panel and click on the - +button to add a new request.
- Fill in an appropriate name for the request and select the Firebase app to be used for the request. Then, under the method, choose - Create Item. 
- Under the - Path, fill in the full path to the collection in your Cloud Firestore database.
- Add the data of the new document to be added in key-value pairs. 