What is base of share marketing,?

I want to know why share value increase or decrease in share market. total share sale or purchase of any company in share market or only 49%. Reliance company is a private company and its owner Mukesh Ambani, mai janna chahta hu ki jab share other person puchase karte hai to kya utna share ka owner purchaser hoga or jo first time company create karta hai aur capital apne hi lagata hai. Mai janta hu ki company 3 month par or 6 month or 1 year par dividend decalrd karti hai but company share price increase or decrease daily base why?