Hi...
You need to first find out why can’t you smile confidently is it because of your teeth placement, their color or shape or size or what, any cavities, because of the size or shape of the lips.
If you have one of the above reasons you can go for dental and cosmetic treatments for getting a perfect smile.
If not then you’ll have to work on your confidence, look into the mirror and practice you’ll gradually get there.
Next Steps
Consult a dentist online/offline for best treatment options available