How to get saved data from firebase list

I m trying to make work a project to insert Letters is textboxes save them to firebase list and if someone is save more the with load button to get the new values from firebase
I manage to save ok in firebase but I cannot manage to get them back .
And why it is not possible to store in firebase a global variable as list ?
I put it inside a procedure to save it .
I cant make it please any help