How can I make a local webpage inside my website

Question

Example:contact us in Facebook

Answer 1

You can use <div> as a container for your whole contact us page,

<div id="contactpage" style="display:none;">

<!-- WHOLE CONTENT HERE -->

</div>

Why I added display:none? Because I don't want it to be displayed yet, but only when the user presses CONTACT US button.
So on that button make a onclick event

<button onclick="openContactPage()">

openContactPage is a function which you now have to make inside JS.

function openContactPage() {
contactpage.style.display = "block";
homepage.style.display = "none";
}
so now homepage would disappear, and contact page would appear.