A fileset is a Concrete5 term for a collection of files grouped by association under a particular name. This block uses your selected Concrete5 file set to display the relevant images.
To create a fileset, either upload a selection of files or select a range of files in the File Manager and edit their attributes. This will give you the option of adding files to a File Set.
Give your file set a unique name, so you can easily identify it later.