save accelerometer data on real time firebase

I am using the default app from expo documentation to see the accelerometer’s values. I need to save those values in real time and after research i found rnfirebase. My question is how could i do that? Any ideas? I am new in javascript so i have too many difficulties and i try to figure this out line by line.
All the examples i found are about personalized data. I care about one person and I do not know how to save the data from the app in an array.