While you are experimenting with these facilities you will make mistakes and want to go back to where you were.
You can go back one stage at a time by clicking on Edit > Undo xxx, or Ctrl-Z.
In Photoshop you can also achieve this with the History palette. This displays the last 20 actions on your image. Click on the one you want to go back to.
Most software packages have an 'auto adjust' or 'auto enhance' facility. Try that first - it often improves an image quite dramatically and may well be all you need.
In Photoshop Elements it is found on the Enhance menu. The options include Auto Levels, Auto Contrast, Auto Color Correction, Auto Red-eye Fix and Auto Smart Fix. The latter aims to make all the corrections in one click - it may work brilliantly (or it may completely wreck your image).
Photoshop Elements - Enhance > Adjust Color > Remove Color Cast
In the old days you would get a pronounced yellow colour cast if you took photos under tungsten light while using daylight film. Digital cameras usually make a pretty good job of correcting for the ambient light but do not always get it right.
Make sure the 'preview' box is checked. Then click on an area of the image which should be a neutral grey. If it still doesn't look right, try clicking on other areas that should be grey.
Photoshop Elements - Enhance > Adjust Lighting > Shadows/Highlights
If you have a very contrasty image this tool can help by darkening the highlights while lightening the shadows at the same time, often revealing more details in both the dark and light parts of the picture.
Photoshop Elements - Enhance > Adjust Color > Color Variations
Perhaps the easiest way to get the colour balance right. Most packages have something like this. The original picture is shown at top left and 6 possible colour variations are shown at the bottom. Click on the best one and that moves to the top right. Keep going until you get the colour you want, then click 'OK'.
You can change the lightness as well with the 2 pictures on the right.
For the greatest control set the 'Amount' control to a fairly small value.
You can adjust the shadows, highlights and mid-tones separately, though usually you will only need mid-tones.
Photoshop Elements - Enhance > Adjust Lighting > Brightness/Contrast
You can use this to make small changes to brightness or contrast but it does a poor job (usually resulting in washed out highlights or muddy shadows). Use Levels or Shadows/Highlights instead.
Photoshop Elements - Enhance > Adjust Color > Hue/Saturation
Saturation makes your reds redder, blues bluer, etc. Use it to brighten up a picture taken on a dull day, or to tone down an over bright picture. But don't overdo it.
I recommend you do not use Hue or Lightness; there are much better ways of achieving those effects.
Photoshop Elements - Enhance > Auto Smart Fix or Adjust Smart Fix
Try it - it may work. Auto is one click. Adjust allows you to adjust the effect so gives a little more control. If it doesn't work, go back and use the tools above.