Hello my friend. ADD children have a very difficult time focusing. When you tell him to do something, at first give him a one step direction such as clean up the clothes in your room. Be specific as to what you want him to do. Then praise him for a job well done and move on to the next task that you would like him to complete such as put all of your toys away. You may even want to have all of the tasks listed on a checklist that your son can check off when he accomplishes them.
ADD children get rather discouraged very easily as well as sidetracked. They are very self critical of themselves as well. Your goal is to get your son to focus on one task at a time and complete it. You must also foster self esteem by praising even the smallest accomplishments. Be consistent and you will see results. If you need more assistance, please ask. My 10 year old has ADD so I am very familiar with your struggles.