To make this really simple, baking is a method of cooking where you surround the food with hot dry air. The two biggest problems that most people have with baking is that they trust their oven and they trust a timer.
In order to make great food you have to pay attention. Chances are that your oven at home is misgauged so that it’s not really 350 when you think it is so you have to keep an eye on whatever you’re cooking. Even the placement of an item has an effect since most ovens have “hot spots” and thus the food needs to be rotated to ensure that it’s cooked evenly.
Roasting and baking are more or less the same idea only that baking typically refers to breads and pastries and roasting refers to the same cooking process, only involving meat and sometimes root or bulb vegetables.