Saving to containers nested in parent objects, Firebase, IOS

I’m trying to update a user bio from the empty string I made during account registration.

Currently I have

let bioupdate = FIRDatabase.database().reference().child("userbio")

This goes into Firebase database and attempts to find the empty
container “userbio” however userbio is nested inside of it’s parent

I know something is working because it creates a new class inside of
the database console on firebase and names it “userbio” with the updated

I call the action with

@IBAction func updateBio(_ sender: Any) {



I am currently logged in with the user I would like to update the
information for. However I’m not quite sure how to get the program to
locate the right UserID and furthermore the right container.

when I used the code

let bioupdate = FIRDatabase.database().reference().child("users").child("userbio")

nothing updated at all.