How can I sing better, how to reach high notes with power?

How can i sing better, i sing in tune with a nice tone but want sound better, what exercises can I do, and how do i sing using the diaphragm?

Singing from the diaphragm is a natural occurrence if you take a low breath. Just make sure that when you breath in your stomach drops and your chest doesn't come up. Breath support is the result of a good voice that is developed by balancing the air from your lungs with the muscle of the voice. If you concentrate to much on your breath you will over power your voice with air. This leads to fatigue and straining. So when you practice make sure that it is easy. A good strong tone is something that is built in over time and not something that you can just get by squeezing from the diaphragm. If you just go strait for the diaphragm you will get a stronger tone but you will have a harder time making the high notes sound nice.

Look into Speech Level Singing and the at home course called Singers Advantage.

deep breathes

each day practising holding breath

sing range of notes
do ray mi far...

do it first quiet, then get louder and louder

you need to breath from your lower lungs and back so try putting your hands on your hips and breath to there while counting to eight and hold the breath... for high notes try dropping your jaw when singing high and working on your lower range will add notes at the top...
hope this helps.. :)

Your Diaphragm is used when you sing with your stomach. It's good to practice singing while focusing on keeping your stomach pushed out. You have more power in your voice this way. When you talk with a deep voice, you talk with your diaphragm.

Just remember, having power means you might over do it. (your notes become sharp)

I'm sure you do, but if not, practice to a CD/MP3. I'm not talking rock or sreamy metal garbage, but soft stuff like accompanied Jazz. Something that you can really emphasize your pronunciation, and hear yourself match, or not match the notes in the song.