Shown as plain text

Sorry, I’m kind of new with WP-PHP…

I installed the plugin and I created a new page with this basic code:

<?php
echo "<h1>hello</h1>";
}
?>

THE RESULT IS: (Hello is shown as <h1>)

echo “
hello

“;
}
?>

What am I doing wrong?

thanks

https://wordpress.org/plugins/php-code-widget/