Help i need more confidence?

am 14 and i was bullied so i moved schools so my confidence have been knocked down haw can i get it back? i am so shy at school now and befor at my old school me and my mates use to rule it befor i get bullied by them and went :/ everytime i go out paranoid like everyone is looking at me even at school :/ i need help haw can i get my confidence back?