If you want better photos,you will need to learn to use a photo editing software. There are some excellent, free and simple ones that go with windows , with sliders that will help you improve any of your shots. Just right click “open with” on your picture to see the options that you already have.
1.Windows photo gallery is a standart photo editor for vista users. even has a “auto adjust” function for the first time users. Even though it will help in most of the cases, there will always be exceptions where you will have to adjust the pictures manually.
2. Windows Live photo gallery also is another free possibility. it has some extra correction options like red eyes, rotation and black an white effect. Absolutely sufficient for a start.
For professionals editing is way more complicated. See > What is workflow.