<div class="profile"> <h2>hello<br> <span>Welcome to my CV website</span> </h2> </div>加一段jQuary

Sure, here's an example of how to add a jQuery script to modify the HTML:

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
<script>
$(document).ready(function() {
   $('.profile span').css('color', 'blue');
});
</script>

This script will change the color of the span element inside the div with class "profile" to blue. You can modify it to perform other actions on the HTML page.