It is perfectly okay to not know it all. It is perfectly okay to be young and not have had much experience. Everyone had to start from somewhere. So do not feel less than or inadequate because of your lack of experience. It is perfectly alright. Acknowledge that. But what is not, is thinking that whatever you have is enough and that you do not need to gain any more. Inexperience can always be supplemented with the strong desire and eagerness to learn more, develop the skills and acquire more of it. It is essentially about attitude. Experience can always be acquired. But attitude is something that needs to come from within. With the right kind of attitude, anyone can do what they set out to do, even with the lack of experience.