Create a new repository named username.github.com, where username is your GitHub username.
On the repository page, click the creating a new file link.

index.html. Now copy and paste the following code into the file.
<html>
<body>
<h1>YOUR NAME</h1>
<p>Welcome to my website!</p>
<img src="https://media1.giphy.com/media/KasZzipEr3khqtCAIv/giphy.gif" />
</body>
</html>You can customize the text that says YOUR NAME and Welcome to my website!.

Commit new file button.
Your website is now accessible at https://username.github.io!

