Problem scenario
You know how to find the individual postings. You know how to find the main pages in WordPress. But how do you find your advertisers and sidebars on your site (to edit them)?
Solution
In WordPress, go to Appearance -> Themes. Choose the theme that applies to your site. On the main part of the screen, click/browse to the area of your site that has the blocks, columns, sidebars and/or advertisements. On the left click on "Widgets."