If you want to understand detachment, you can read a great deal about it here:
Law of Detachment - Flowing with God » Secrets of Mind and Reality
You should have a goal, an aim or intent about a certain outcome you want to achieve. Detachment means that you become someone who doesn't have a care in a the world about whatever obstacles and challenges you may face towards the fulfillment of that goal. You are aware of what problems you may face but you are detached from them, focusing solely on your intent only.