Fairy.Spence said:
Every time I try to sing higher, my voice cracks and I stop because it sounds terrrrrrrible.
The range where you start to shift between "head voice" and falsetto is often really bad for untrained singers. I had a huge problem with it for a while despite years of training with a wind instrument. Do some slow scales/arpeggios, focus on pitch accuracy and maintaining good tone. Slower is almost always better until you have absolute control. That control is key; you have the equipment to hit the desired notes, you just need to learn to harness it properly.
EDIT: whoops, wrong voice ranges. Don't know what I was thinking.