Second step is, don't stop singing! even if your sister, brother or friends keep telling you that your voice is terrible don't stop singing, if you are ashamed find a place where nobody can hear you then practice, practicing helps your voice to improve its tone day by day.
Third step, record your voice, sometimes we don't know that we sound terrible already, recording your voice and listening to it will help you to determine the things you need to fix with your voice or your way of singing, then after listening to it , record another one but this time make adjustments so you will not sound the same way as before.
Fourth step, join some organizations or group of friends who love singing, learning is more fun if done with friends, it boosts your confidence to be more expressive in the way you want to sing.
The fifth and final step is, don't lose hope,may people will judge you and criticize your voice , but don't listen to them just always remember that everybody will not appreciate your voice,just do it for yourself not for everyone else and if you really like something, you do everything for it, just be happy and continue singing!