Mit inventor and realtime firebase

Please i need help! I'm not a programmer but I try to learn in my free time.. I have started a simple project in mit inventor with which every user have to register and login and then choose a number from 1 to 1000 for taking part in a draw. Until now I have connected the app with firebase auth and realtime firebase. When somebody login and pick a number, I see the information in realtime database. But when another email login and pick a number the data in realtime firebase just changing without storing the first user's info. In firebase the rules are "true" , I turned (for testing ) in ```
"auth.uid != null" , but i see nothing in database when i pick a number. Also I would like every logged in user pick a number only one time without can change the choosing number.

the user data i want to appears in database i'd like to have this form : user 1 : email xxxxx, number xxxxx datexxx , user 2 ....