Page 2 - Working with resizing the photo and applying correcting techniques.
Decide how large your finished
image needs to be so that you can resize it.
Do this now rather than wait until the end, so that when you sharpen
the photo you'll be viewing it at 100% (that's very important). You may
need to use the normal viewing button (on the custom tool bar) for the
photo to be viewed at 100%. It's second from the left. 
Now here's a tough one for beginners to work with ... the Histogram adjustment dialog box. There is so much to learn that I won't go into any of it here. But here's a link to a really fine article entitled Improving Contrast/Brightness in Photo Images with the Histogram Tool by Wayne Fulton who just happens to be the 'authority' on scanning. It dates back to June 2001 but nothing has changed! Plow through all the text and do lots of experimenting and practice until you acquire the knack. Here's another article which goes into even more detail:
A PRACTICAL GUIDE TO INTERPRETING
RGB HISTOGRAMS
If you're using a digital camera with a histogram thumbnail
that you can view, be sure to see page 4. The article is long and wordy
... at least look at the pictures!
One more 'definative" resource:
Understanding
Histograms
from Luminous Landscape.
You may want to explore the possibilites that this tool - Brightness/contrast offers also. But don't over-work an image with too many alterations.
Now let's look at the Auto Color Balance tool. With each of the tools, you'll want to pull the dialog box over next to or slightly on top of the photo. A reminder:click the proofing button on and off while looking at the photo, not the little box.
Automatic Saturation Enhancement. This one is tricky. I wish they had used a slider. There are just so many variables here. Experiment until you like the results. Don't get carried away with this tool, or any of them, as a matter of fact. I exaggerated the effect here.
On to page 3 and the Clarify tool, using the unsharp mask and the JPEG optimizer.