Hey Dee (and everybody else that might be interested)
Feel free to move this if you think it can be better someplace else. I don't come back here into the photo forum much, cause my camera flooded.
But, now I have my new cheapo point n shoot, I am sure I will be here more...
Anyways...
I have been using Photoshop since version 4, and while I have not done a lot of underwater photo manipulations, perhaps I can help answer some questions.
Digitally enhancing photos can be very cumbersome even with a good mouse. I would highly recommend getting a tablet with a pen stylus. I have a 6x8 Wacom tablet, and refuse to do any photo editing without it.
When I work on a project, I ALWAYS work from a copy. That way if you screw up, you still the original to import back into the copy and if you want to try variations, you have an original to work from.
First. Learning Photoshop. Highly recommend getting Adobe's Classroom in a Book. This is the same book that is required when taking a Photoshop class in some colleges. Even if you get an older version (try amazon.com or half.com for best prices), you will get a good overview in what PS has to offer, along with a CD with working files for each chapter.
Second. Layers. Layers are your friend. Think of layers as sheets of transparancies laying on top of each other. Each item then can be digitally changed, moved, resized, whatever without affecting the rest of your work. Referring to the original again, I make a copy of the original layer. Lock the original layer and hide it. Now you are working on the copy. You can drag or import additional pics into the working file, change each, and you end up having greater control of the final image. For instance, say the image you drag in to its own layer, you change the hue, it will only affect that layer.
Third Magic Wand. The magic wand selects only that color. You "tap it" on a particular region, and it select that color only. Works great if you want to select a large region say, a white backround, but is cumbersome if you are trying to select an area of a photo and end up with only a few pixels selected. If you want to select all pixels in the image (on that layer) of that color range, you have to Select> Grow, or Select > Similar. Then the selected areas are the only areas you can manipulate. A good example of using this feature would be selecting a dark area to try to lighten it without lightening the whole image. The marching ants (what the line is called of the selected area) can make your selected area hard to see when you make changes, so I hide the marching ants with CRTL + H. Just remember you have hidden the marching ants, otherwise you will get very frustrated when you try to change another area and nothing happens. To Deselect the area, use CTRL+D.
One thing the book will help you with is the masking feature. You actually "paint" the area you want selected. Works great for getting in intricate areas, but this is getting rather involved....
Hope this helps.
.... I think my wallet just fainted 
