Start by creating a new Block in the CMS editor and giving it the title of "bannerAd1". Put some text in there an image with a link to some special offer. Once this Block is saved it can be displayed in either your content or another block, throughout your website by the simple inclusion of the rich text markup

Usage

{block name:"bannerAd1"}

name
The name of the Web Block. Blocks cannot share the same name, so make sure each in unique.