First thing first, you must upload your favourite icon using ImageShack. Then, sign in to your blogger.com and open 'Layout' then 'Edit HTML'. Here is the text :
Add this bold tags to your template. Simply put them in head section, between "title" tag and "b:skin" tag. If you face difficulties in finding the tag, just use the find tool in your browser.Click 'Preview' if you wanna make sure its working or not but i'm highly sure that its working. Then, click 'Save Template' and finish! Have a try! Good Luck!