...you have clearing stated in your title, she has low self-esteem. So the problem is how she can help herself to gain confidence...
self-esteem is the overall evaluation or appraisal of one's own worth. 中文是自尊 self-respect is a proper sense of one's own dignity and integrity 中文是自重...
...wikipedia.org/wiki/Self_confidence In psychology, self-esteem or self-worth includes a person's subjective appraisal..., not physical features. In addition, self-esteem is the third most frequently occurring...