Are you sure that you annoy people? If so, have you any idea what you may be doing that's annoying? The first thing is to try and decide whether you're doing anything to provoke this, or whether you're being treated unfairly (it can happen in a group situation, especially at school or college, that one person gets picked on: This is really unfair but if so, it may not be anything you are doing at all).
However: If you think you are not good at getting on with people, there are certainly some things you can do. The first is, starting from now, to treat people the way you would like them to treat you. For example, try not to act aggressively or seem to think you are better than others; equally, don't be too eager to fit in as this can look weak. Calm, generally friendly people, who don't get upset too easily or try to upset others, are always generally liked. And if you are dealing with aggressive or bullying people, then don't waste your energy trying to make them like you - just get away from them.