Singing

Singing???
What does it mean to “Sing from your diaphram” [sorry if spelled wrong] and wats you head voice, chest voice and all that jazz. How do u get a good tone? Im doing singing in 3 different choirs and have a teacher and all of them talk about that im always confused about it and when they try to explain i get even more confused! Answers are greatly appreciated.
also another thing im wondering about is when i sing, i kinda sound like im gonna crack and stuff. Why??? Im told im a soprano but when i sing “God Help The Outcast” i sound like im going to crack and i sound scratchy. Why?
No clue!
Greyson Chance Singing Paparazzi