Photoshop Elements 6 shipped with Camera Raw 4.2 (Win) or 4.3 (Mac)
http://helpx.adobe.com/x-productkb/global/camera-raw-compatible-applic ations.html
Both very outdated.
Which camera make/model are you trying to use ACR with?
Camera makes/models and compatible versions of ACR are listed here
http://helpx.adobe.com/creative-suite/kb/camera-raw-plug-supported-cam eras.html