What are varous roles of each nutrient

Hi I was wondering what the various roles of each of the following nutrients are and what happens if you are to have too little or too much of each:

1. Calories
2. Protein
3. Carbohydrates
4. Sugar
5. Fat
6. Saturated Fat
7. Fibre
8. Salt

Thanks for any help.

Loads of info if you look

There's loads of informative websites out there that describe the roles of nutrients and what effect too much/little of them can have on you. Try looking in a search engine...