What should I do to increase my confidence drastically considering my confidence level at 2 out of 10-point scale? If I have a year to do so, can you provide me a detailed recipe?

There is no better way to learn swimming than to jump in the water, start doing things that you are afraid of, lack of confidence is lack of courage, try your courage out, it is just the fear that has taken over you. Fear is 99 times imagination only, you think that it is low confidence but thinking changes with time, every action has got an equal and opposite reaction, give it a chance, just act.