Today I just learn how to upload my favicon icon, fisrt you need to have an icon with 16 x 16 size image actually, no more no less, go to "design",
look for favicon element then click edit, upload your image, then you can check it through your url, for example: http://yoururl.blogspot.com/favicon.ico. After that, you need to add code between
<link href='http://yoururl.blogspot.com/favicon.ico' rel='icon' type='image/x-icon'/> <link href='http://yoururl.blogspot.com/favicon.ico' type='image/x-icon'/>
That's it, you are done. Congratulation!