The Search Criteria tab is where you tell Duplicate Cleaner what you are looking for. (The Scan Location tab lets you say where).

 

There are three modes of operation - Regular Mode, Image Mode and Audio Mode.  Select the appropriate tab to activate this search type, and then specify the criteria.

 

On this page you also specify the Search filters - these narrow down the type of files you are scanning for.  You can also refine your search with More duplicate options and Advanced search options.