Good answers above. The unsaid point is that Adobe stopped updating older versions of Camera Raw to be able to read raw files from newer cameras whenever they released a new major version of Photoshop. Thus, because your camera is newer than the latest update to Photoshop CS5, the version you have is no longer receiving updates and will never directly be able to open your raw files.
Since your version of Photoshop cannot support your camera directly, as JJ mentioned above you can download and install the latest version of the free Adobe DNG Converter, which can take your raw files as input and put out DNG format files, which your version of Photoshop can open.
Photoshop Help | Digital Negative (DNG)
The DNG converter DOES work, and you will be able to open the converted DNG files with your version of Photoshop, but if you want maximal quality from your raw files (not to mention the convenience and ease of use of directly opening your raw files) you'll want a newer version of Photoshop. Adobe has made substantial improvements in raw conversion quality in recent years.
Note the availability of the low cost Creative Cloud Photography bundle:
Creative Cloud free trial & plans : Adobe Creative Cloud
-Noel