To become a famous singer, you need to find a singer or vocalist that inspires you. This will enable you to take your music to the next level. Pick a song and listen to the singer to memorize how they sing. Do not fear, sing in public whenever possible.
Practice, practice, and more practice! You have to have the talent. If you don't, try lessons. Find a record label or try to audition for a show such as x factor, the voice, American idol, or America's got talent. Hope it works out for you!