How To List All Posts Filtered By Category

On the sidebar find the widget with buttons:
DISPLAY, CLEAR, ADD, REMOVE, SUBMIT
Using this widget you select any number of categories
and then click on SUBMIT to create the list.

• In the pop down click on a category.
• Then click on ADD to put that category in the list
• DISPLAY shows your choices so far
• CLEAR will empty the list
• To remove a category from the list
  click on that category in the pop down and click on REMOVE
• When you are satisfied with the category list, hit SUBMIT