The Filter Templates dialogue box contains 2 groups in the Root folder, sorted by Filter group and Transition group.
The Filter group contains further Folders, which in turn contain numerous effect templates that are ready for use.
The Transition group contains further Folders, which in turn contain numerous effect templates that are ready for use.
To select a Filter template, go to a Template folder (e.g. Filter group / Sparkle), where effect templates are displayed. By double clicking on the effect of your choice, you will transfer it into the preview window.