How to insert to Realtime Database under the child?

How do I do the code in Java to create an instance like in the image? I am trying to create that but it only inserts under the Teacher parent.

Below is the code that I am trying to do.

FirebaseDatabase.getInstance().getReference("Teachers").child("Accounts")
    .setValue(dataClass).addOnCompleteListener(new OnCompleteListener<Void>() {
        @Override
        public void onComplete(@NonNull Task<Void> task) {
            if (task.isSuccessful()) {
                Toast.makeText(AddSection.this, "Section added successfully", Toast.LENGTH_SHORT).show();
                finish();
            }
        }
    }).addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception e) {
            Toast.makeText(AddSection.this, e.getMessage().toString(), Toast.LENGTH_SHORT).show();
        }
    });
}

If you want to add a new child in a structure that looks like this:

db
|
--- Teachers
     |
     --- Accounts
          |
          --- 0000-123455
               |
               --- Sections
                    |
                    --- BSIT201A
                         |
                         --- Students
                         |    |
                         |    --- studentName: "Joseph"
                         |
                         --- pSectionName: "BSIT201A"
                         |
                         --- subject: "Subject Name" //👈 Newly added.

Then you have to create a reference that points to the BSIT201A node and call updateChildren(), like in the following lines of code:

DatabaseReference db = FirebaseDatabase.getInstance().getReference();
DatabaseReference secNameRef = db.child("Teachers/Accounts/0000-123455/Sections/BSIT201A");
Map<String, Object> update = new HashMap<>();
update.put("subject", "Subject Name");
secNameRef.updateChildren(update);

I also recommend you attach a complete listener to the updateChildren() operation, to see if something goes wrong.