Boiling things using salt Since recently i have to cook for myself and a lot of products mention i should boil some water with salt and when it boils add the product.

Why on earth do you have to add salt to the water?
This is generally to season the thing being boiled whilst it is cooking.  The salt will infiltrate the innards of the thing being cooked infusing it with some seasoning.

Try with something basic like pasta or rice to see the difference between cooking in plain water and cooking in salted water.

This quesion and this one might also provide some insight.