It helps to make ur code neat
<?php
if (isset($_POST['Submit'])) {
if (isset($_POST['event'])) {
echo "you chose the following day(s)<br><br>";
foreach ($_POST['event'] as $value) {
echo $value . "<br>";
}
} else {
echo "you did not choose any days";
}
}
?>
Looks like it is all correct, you may want to make sure everything is spelled correctly.