With all the varying degrees of inattention, hyperactivity, impulisivity that can be found in each person, no one knows all the answers from personal experience. It helps to talk to someone who has some experince with it. My experience with this comes from the point of being a teacher, a parent, and most important, an ADHD person myself. This is a problem that plagues many people. Many of them really don't realize that there are things they can do to cope with it.
ADD is a problem in the brain.
It is mostly noted in children who cannot pay attention in school. ADHD is all of that without the ability to sit still for more than 2 seconds. It's hard to be a kid with this. It's taken me a while to decide to publish what my life in school was like. The length of this story may change from time to time.