Sort by date colum

Hello,

hope someboy could help me ?
I would like to sort the following table by date of the 1. column “$beginn”. The dates in the database are stored in timestamp. And if possible it sould only show future dates up today. What do I have to add to my code ?

// check if the repeater field has rows of data
if ( have_rows('t_block') ) {

 	// loop through the rows of data
    while ( have_rows('t_block') ) : the_row();

		 $beginn= get_sub_field('beginn');
		$ende= get_sub_field('ende');
		$preis= get_sub_field('preis');  

        // display a sub field value       

           echo "<tr><td>" . $beginn . '</td>';
           echo "<td>" . $ende . '</td>';
           echo  "<td><a href='" . get_the_permalink() . "' />" . get_the_title() ."</a></td>" ;
          echo "<td>" . $preis . '</td></tr>';

      /*
      */
    endwhile;

} else
{

    // no rows found

}

Thank you for your help !!
https://wordpress.org/plugins/advanced-custom-fields/