Admin > Content Management > Web Contents

Select content type Pop-Up Window in the drop down. 

Create New Pop-Window

Create the content in the same way as a Corporate Page

Save

Add link to Pop-Window on Content page

On any content page or content area, include this piece of code (click tools and source in content editor), 

<a href=void(0)" class="popupwindow" data-documentname="Delivery">

Example: 

For full details on delivery 

<a href=void(0)" class="popupwindow" data-documentname="Delivery">click here forFull Details on Delivery</a>

Where "Delivery" is the name of the pop-up Window. (i.e. replace Delivery with the name of the pop-up window you just created )

See also: Create Content Page