how can i build self - confidence? give Advice/Suggestions

Well, for starters you could do something that everyone can't, an example of this is being Determined on a subject that you know or mastered like Drawing while some your friends can't. This will build a little self-confidence or Determination of yourself.
and little by little you will feel that self confidence that you wanted to feel.
(I'm talking from experience so I hope this helps :D)

The first one is, don't compare yourself with others. You know, if you're comparing yourself with others you would feel small. Be positive by killing negative thoughts such as 'I'm not worth it' or 'I'm not smart', etc. Just don't think about begative thoughts that makes you feel small and depressed. Also, always be grateful and keep smile. That way you'll get your confidence, little by little