To enable the filters simply go to the article settings and check the appropriate box. Once the fields appear you can choose the Javascript handler you would like to use for filtering and define the available filters.
The filter value is an internal ID for the filter. The allowed characters are only alphanumeric characters and the dashes (this value will be used as CSS class). Hint: to create the "Show all" button do not enter any value.
The label is a text value displayed on the filter button.
As an extra you can also enter the CSS class per each filter button and give it a special styling.
Once you got the filters ready, you can start assign the content elements to appropriate filters. A content element can belong to one or multiple filters. If the filters are not assigned at all then the content element will not be filtered.