child is added to the specified Firebase reference. Firebase postRef = ref.child("posts"); Map<String, String> post1 = new HashMap<String, String>(); post1.put("author", "gracehop"); post1.put("title", "Announcing COBOL, a New Programming Language"); postRef.push().setValue(post1); Map<String, String> post2 = new HashMap<String, String>(); post2.put("author", "alanisawesome"); post2.put("title", "The Turing Machine"); postRef.push().setValue(post2);