How Does It Work?
ESRI has pulled through and given a lot of information about how to configure and use the CSW Client. Read through their help documentation completely and you should have a firm understanding of how the client works, and how to customize your own configuration. Their documentation is available HERE
CSW is a "loose" standard, in that it allows lots of flexibility as to how it is implemented. It is also regularly changed and updated. Some of these changes may make previous iterations inoperable. In order to try and work with the largest possible number of these variable services, the ArcGIS CSW Client allows you to define your own collection of Catalogs and Profiles. While this makes client configuration a little more difficult, it allows greater flexibility to work with different CSW implementations.