Fine-Tune the Fix
Here is what my photo looks like after a little dodging in Photoshop Elements.
As always with image editing, if you think you're overdoing it, you can use the Undo command to revert to a previous state and start again. You can tweak the tool's settings in the toolbar at the top of the screen, too; depending on the resolution of the photo and the size of the underexposed region, you might want to modify the size of the Dodge tool.
And rather than dodging the original photo, it's a good idea to work in a layer on top of the original photo. To do that, duplicate the layer before you get started by choosing Layer, Duplicate Layer and clicking OK. Now you can modify the top layer and use the opacity control (in the Layers palette on the right side of the screen) to fine-tune the effect. The original photo is still underneath, preserved in case you need it. For more tips, read "Layers 101: Improve Your Photos by Editing With Layers.