how to boil water:

Put water in a pot large enough for the amount of water you're adding, then turn the heat up to high. When bubbles start rising to the top of the water, it's boiling. Sometimes one might throw salt in the boiling water to add flavor to the food being cooked. Scientifically speaking, adding some amount of salt raises the boiling point, yet people say water seems to boil more quickly with salt. It probably just gets to a rolling boil faster with the added impurities, making for a more violent boil. Not sure.

Most of the time, you'll need to reach a rolling boil to cook pasta or noodles or dumplings. A rolling boil means the water bubbles and rises so much it looks like it's rolling into itself.

Water does boil away, so in some dishes you'll have to take the reduction in volume into account. Likewise, the pot needs to be bigger than just the water if you'll be adding food to it. You don't have to stand over the pot, but don't let it boil dry or you'll stain or burn the pot.

I do not usually put a lid on a pot with only water in it. A lid helps it heat up faster; I just find it easier when I don't have to keep lifting the lid to see if it's boiling. Lids are important, however, for cooking many basic foods like rice and hard-cooked eggs.