Unclear Checkbox value

i have the task of making a table of wich you could select specific rows to print on paper, since the table its quite large and was alrady made by someone else (who is not around anymore) i got no one to help me understand. i made it to the point where i placed a checkbox on the left of every row, but i cant (o more specifi idk how to) make it so you only press a button and print every checked row.

this is part of the code where the checkboxes are inside a foreach loop. thaks in advance.

"; ?>

                                <td style="background:<?php echo $Color; ?>;font-size:10px">
                                    <b>
                                        <?php echo $row['Semana'] ?>
                                    </b>
                                </td>