To add favicon image in website you can just follow the following steps.
Firstly select the image you wanted to make as the favicon image for the website.
Resize your particular image to 16 by 16 pixels so that it can fit for the browsers tab.
Generate favicon image for the same.
Add this favicon image into your website's image folder.
Finally add the following code into your markup page.
<link rel="shortcut icon" href="~/images/favicon.ico" type="image/x-icon" />