A virtual section is a place where you can find all the threads pertaining to one subject. I have a Miniatures VS and a Rhonda's Workshop and Clases VS there are also sections for the Jane Stickle threads The Round Robin threads and more.
Here is a link
http://www.quiltingboard.com/virtual_section_list.jsp
Or
You can click on Home and scroll towards the bottom. You will see a User Defined Sections link click on that and you will be in the Virtual Section with a list of all the sections.