This page showcases various advertisement sizes that can be used on Sidebar A and Sidebar B.
How to create an advertisement block as shown on this page?
In order to place and advertisement, go to Appearance > Widgets. Next, drag a Text Widget into your widget area. Inside the text widget, you can place the dummy code of these advertisements. I have created a sample text file of all these blocks which is available inside the
dummy_data/ folder of your theme.