RAW files in Camera Raw? It usually opens itself when trying to open a RAW image in Photoshop.
If you want to use Camera Raw as a filter: Filter > Camera Raw Filter.
Easiest way is to browse that file in Bridge and right click and Select "Open in Camera Raw" or just double click to open(only for raw files) and it will open in a separate Camera Raw window.
You can do that same from PS as well using Filter > Camera Raw Filter, as already mentioned by Warunicorn.