Download .txt file with code.
Make these important changes:
Replace this “demotitle” with your Facebook username.
with your page name same as above
The timer is set to 60 seconds to change it simply edit timeout: 60
The widget appears immediately after a visitor enters. If you want it to appear after one minute or more then edit wait: 0
To remove the close option, set closeable to false
Add code just before body tags of html.
Go To Blogger > Design > Edit HTML
Backup your template
Paste the code just above body tag