Well, to start I would recommend getting a card reader to download images, its faster and saves using your camera battery, even the cheap as ones work well. Also using a card reader your card will mount as a volume in OS X so you can open a finder window and inspect/copy/move images and files to and from it.
Your camera should have come with a software disk, Image Capture is the program you want, you can plug in your camera and have Image Capture open automatically, then select what you want to download and where you want the images to go.
If you shoot a lot of images on a regular basis, its important to avoid using Aperture/iPhoto to manage where your photos go, you are far better off setting up a good folder structure and manage your photos to suit your workflow.
I use
ImageIngestorPro to import images off camera or card reader, its highly customizable and saves a lot of time once you have it setup for your needs.
Your Canon digital SLR will never show up as a mounted drive when connected to OS X, it requires software to import images off the card while directly connected to the camera.