Save data to Firebase

Im new in MIT, but i now basics in programming.
Im try to build simple app, but have problem with saving data on firebase.
Yes, i use Google and still have the same problem.
I receive message "Previous value was empty"
Can someone help me?

With firebase, it is not possible to append a value to an empty tag. For your first "append" you will need to store a list instead. This requires some conditional blocks in order to make it work.

And block r easy to make program?
Python is easier.

This is a firebase issue, not an AI2 issue.

I just make this on local simple file

A post was split to a new topic: How can I open/read from a file?

Completely different subject, therefore split to new topic.