为了创建一个简单的用户注册页面，你可以使用以下HTML和jQuery代码：
```html
User Registration Page
>
$(document).ready(function(){
$("#registerBtn").click(function(){
var username = $("#username").val();
var email = $("#email").val();
var password = $("#password").val();
if(username === || email === "" || password === ""){
$("#message").text("Please fill in all fields.");
} else {
$("#message").text("User registered successfully!");
}
});
});