What do you have to eat inorder to be healthy? Like amount of food to eat and what kind of food to eat daily?

There isn't one set of foods you need to be healthy.  Being healthy means a lot of things.  For starters, all of your meals should be balanced.  Your "plates" or meals should be of these general proportions:
1/4 plate protein
1/4 plate starch
1/2 plate non starchy vegetables
The exact amount of food you need to eat depends on your body weight and amount of activity. If you want more information on this topic, you can visit mypyramid.gov.