Use Block in Template

Hello everyone are not as if anyone around here has cakephp using the latest version 3 because I will see around trying to use the blocks according to the documentation functions as an include for that I have something like
/src /Auth /console /Controller /Model /Shell /Template /Anuncios /Element /Flash sidebar.ctp /Email /Error /Home index.ctp /Layout default.ctp /Pages /Usuarios
Well in my folder Element is the sidebar that would come to the block you want to use in my home platilla of which in this case is the index.ctp and try to do something like
`//inside archive sidebar.ctp

<?= $this->start('sidebar');?>

//mi codigo html

<?= $this->end();?>`

now within the template for the home that is in the index something
<?= $this->fetch('sidebar');?>
but nothing is displayed