Here's my take on it...
Basketball is a game that requires teamwork and a strategy. In your waking life there may be a situation which requires the cooperation and assistance of others along with a concrete plan in order to achieve a certain goal. It is a situation that you may not be conciously aware of. But through this dream your subconcious mind is trying to tell you something.
Winning in a dream indicates that your subconcious is aware of the fact that you will succeed. You could also be experiencing a new found confidence in your abilities. The dream may serve to offer you encouragement and motivation.
What should you do?
Look at your life from a third person's point of view, try and spot the area which requires team effort. Consciously work towards either contributing to team work or gathering a team to work towards that common goal. Rest assured, according to your dream, the outcome will be successful