Unlike jpegs, tiffs, etc, a RAW file is not an "image" file and the computer has no way of understanding what it is unless it is told.
There are a number of different ways to solve this problem. The cheapest (costs you nothing) is DPP, it's been produced by Canon specially as a "RAW Converter". It simply takes the RAW file, creates an image from it and from there you can either export to another programme such as Photoshop, or "Convert and Save" as whatever file you want (jpeg, tiff, etc) that your software can recognise.
Thats one way, but Adobe provide at least two different means of converting RAW's, and there there are several others.
However, the one big advantage, apart from being free, than Canon's DPP has is that it knows more about Canon's particular RAW arrangements than the 3rd party offerings ever can. Because Canon will not tell them, and why should they!