Onde eu preciso colocar esse codigo?
<android.support.design.widget.FloatingActionButton
android:id="@+id/activity_main_fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:fabSize="normal"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginBottom="16dp"
android:layout_marginEnd="16dp"
android:src="@drawable/ic_add_student"
android:clickable="true"
android:focusable="true" />
