You need to make favicon.
Below is the steps of making favicon:
1. Create an favicon, there are many free online tools that can help you create favicon, actually it is an small image with file extension ".ico".
2. After creating your favicon, please save it to your website root directory.
3. To activate your favicon, you must modify the source of your web page. Add this line to the <head> section of your page:
<link rel="shortcut icon" href="/favicon.ico" />