Note the Histogram which is somewhat left of center...
Step 0 — Bringing your file into Photoshop
Download your images – if RAW, convert (to tiff or jpeg) and bring into Photoshop. I have been shooting RAW just because it allows more control after the shot has been taken. Note: Exposure and White Balance will make a difference on your final result, so there might be some trial and error – in general I leave White Balance to the default camera setting (automatic) and have gotten decent results. For editing, Photoshop Elements 3.0 has worked fine for me. If you have full version of Photoshop you should be in great shape. You can probably get similar results with other software, but I have not tried. For Raw conversion I have been using the Canon supplied software (DPP 2.0 or Zoombrowser & Fileviewer).
So here is the initial image in Photoshop Elements 3.0. Normally I would never look at an image at 33%, but it fills the screen nicely for these screen shots. (100%, 75%, 50%, and 25% give the fairest views of your image.) Note the histogram, which is somewhat left of center.