Edit in JSFiddle

$("#btnGo").click(function(){
   $("#result").text( "Hello, " + $("#txtName").val()  ); 
});
<h2>Hello World</h2>
<fieldset>
    <label for="txtName">Do type your name : </label>
    <input id="txtName" type="text"/>
    <button id="btnGo">Go</button>
</fieldset>
<span id="result"></span>