You need to take him to obedience classes because he is obviously not trained very well and aggressive. PetSmart offers great obedience classes and aren't very expensive.
Your dog has serious aggression issues. Call your vet or local humane society and get the name of a trainer that has experience with this problem that uses non-violent methods. You need to deal with this problem very seriously and you need professional help. You are way beyond basic obedience classes with this problem.