You start at the bottom and with practice and by singing - some singers become major recording artists. And YOU can be heard by the major record labels in Nashville. It all depends on how well you manage your career. You can become a successful entertainer with hit records and appearances at venues all over the country. You will need 3 things to succeed in music.
Music is a career just like any other career.
You must invest some money in your career. You will need a good demo of your singing. If you are serious you will need to receive radio airplay. You can, by working music like a professional, make your music career pay its own expenses. It may come as a shock to you, but even the major label artists pay for their own recordings.