introduce me a nice book for having better self confidence,thank you so much.?

Suzette Hadin Elgin's The Gentle Art of Verbal Self Defense
http://adrr.com/aa/whymastervsd.html

I typed "self confidence" in my library's catalogue's search box. Below are the results.

Do the same search in your library's catalogue. You can see if yours has the books mine has, or you can type the Library of Congress subject headings in the search box. (The British Library's subject heading are probably similar, with a few "u's" added to some words.

By books, I assume you mean novels, here are some that are self-confidence boosters:
-Finding Audrey by Sophie Kinsella
- November 9 by Colleen Hoover
- Paper Towns by John Green
These are all stand-alones, if you're up to reading series, there's the Shatter Me series by Tahereh Mafi.
Happy reading :) Xx