To process a raw file you will need software (a raw converter) such as Canon's Digital Photo Professional (DPP) which is included on the software CD supplied with EOS and PowerShot G cameras.
In addition to all the captured data, the raw file also includes information about the camera settings at the time of the exposure. When you convert an image with DPP, it will open with these settings applied - but you can change them.
Once you have made all the changes, you can 'Convert and save' the image. This will give you a choice of JPEG or TIFF file, but the original raw file remains unchanged. This means you can go back and open it again to create an image with different characteristics.
The navigation and use of DPP is straightforward; here is a simple guide to help you understand the structure. Click a folder containing image files to display them in the DPP window. Then click one of the images to select it.