There are several ways of letting users submit their information to the server. One way is to add the <input> element with the attribute type="submit". Browsers render this element as a button.

When users click on the button, the browser sends the form data to the file in the form's action attribute. What happens to the data later has less to do with design and more with data processing. If you're interested, you can read more about it on MDN Web Docs.^[1]