The ads that appear between posts and at the end of the posts are called inline ads. To show inline ads you have to follow these steps:
Login your blogger account
On the main blogger dashboard click layouts to see page elements
Click edit on the blog post gadget
A pop up menu will appear . Check the show ads between posts
Select size , font ,colour of the sds and again you will see preview of the ads at the bottom.
Click save to apply and save the settings

