Hi Ana,
Welcome aboard the good ship MIMF. As a learning tool to help you to sing correctly, I would humbly suggest a tape recorder with a microphone. Record yourself while singing a melody and then playback what you have sung, listening to how you modulate your voice in regards to dynamics, phrasing and textual diction(can one understand the word being sung). Let your teacher listen to your recording as he/she might be able to better point out your strengths and suggest remedies for the areas that need improvement. I hope this might help you in your quest to become a known singer.
Giovanni :tiphat: