First of all, watch your colleagues, try to understand their work and try to notice their skills. Also, try to get involved in what they do to get the feel of their work. All this to make sure you are really performing better. Maybe their tasks are different and more difficult and your impression may not be that correct.
Then, if you convince yourself that you are really performing better, put your thinking cap on and make a list of things you want: you want more tasks, more responsibilities, some tasks changed, more money or another position in the team or in another team – get prepared. After you have the list, talk to your manager in an honest and open manner telling him that you feel you perform better than the rest of your team and you want some changes. Be open and tell him what changes you feel would motivate you. Be prepared with ideas and arguments, not just demands. Simply showing a list of demands won’t take you anywhere. Maybe your manager has been too busy to notice all your daily activities and doesn’t know the status of your work as well as you do. Giving clear arguments and examples will support your cause.
Also, offer to help your manager with some of his tasks if you feel you are up to the challenge – ask for small tasks at first and them get involved in more important ones to prove yourself.
Then, if changes don’t come quickly, don’t be disappointed. Maybe the company can’t offer you more that what you have at the moment. Try to learn more, try to get involved in as much as possible, keep all your options open and changes will come for sure in the end.