cant hold breath for a long time underwater

Question
Hello sir
How are you? I am from India. Last year i joined swimming classes but quit because i couldn't hold my breath for more than 15 to 20 seconds and would end up swallowing water and had to come out of water for breath. I saw my friends could breathe underwater for a long time and they had some techniques.
The coach told me i couldn't do it and that i panic. So i have lost a little of my confidence. I want to try again now. So can you tell me what can i do to stay underwater for a long time?

Answer
Sahana--
Learning how to breath while swimming takes practice.  You coach was wrong telling you that you CAN'T do it.  Your friends aren't breathing underwater, they have learned to breath correctly while swimming.  Take your time and learn the correct way to do it.  Don't let  yourself get discouraged.  It takes practice, watch your friends and see what they are doing and try to follow that.  I can't really teach you without seeing you.  
Hope this helps,
George