Another way to Dodge & Burn in Photoshop 7.0....
For the Dodge part...
Create a Solid White layer. Mask it. Change this layer to Lighten. Then, use Eraser tool (Brush mode) in very low opacity (maybe 25%) to erase the areas that needs to be lighter. If necessary, turn on the Airbrush mode (under the Eraser tool) and adjust the Flow control. Make sure that Foreground color is Black and the Background color is White so that you can erase the mask.
For the Burn part....
Create a Solid Black layer. Mask it. Change this layer to Darken. Then, use Eraser tool (Brush mode) in very low opacity (maybe 5%) to erase the areas that needs to be darker. If necessary, turn on the Airbrush mode (under the Eraser tool) and adjust the Flow control. Again, make sure that Foreground color is Black and the Background color is White so that you can erase the mask.
If you lighten or darken the areas too far, just change the Background color to Black and erase one of those areas so that you can bring back the lightness and the darkness of the areas without messing up the original.