Follow these Steps
(1):- Go to blogger site. Open Blog in which you want to add banner ads.
(2):-Go to Layout and click on Add a Gadget.
(3):- New window will open and you will see empty space in it.
(4):- Copy below code and Paste it in empty space(You don't need to add any title ).
(5):- Replace "Advertiser URL" with the link of ads page or website you have given.
(6):- Replace "Image URL" with the image Link and that image will be visible on your website.
(7):- This is typical setting for 125x125 image ads. You can change it as you need by Just Replacing (width="125" )(height="125") red colored Values.
(8):- Click on save and view your newly added sidebar banner ads.
Demo View: Click Here
That's all for today. Hope you will like this article. If you face any problem do mention in comments.Have a nice day.(If you like don't forget to subscribe).