Choose the banner you would like to use.
https://www.sfimg.com/Resources/MarketingCenter
Copy the HTML code.
Log in to your blog. Go to 'Appearance' and click on 'Widgets'.
Drag the 'text' widget to the sidebar where you want the banner to appear.
Open the 'text' widget by clicking the arrow in right corner.
Paste the HTML code.
Click Save.