Just keep trying and trying you'll finally get it and if you dont then just sing soft songs like you said you can notes when you sing soft at my school they have a course that teaches you how to sing and i use to be crap and now im great so keep trying

or try this

Words of Inspiration
To be nobody but myself — in a world which is doing its best, night and day, to make you everybody else — means to fight the hardest battle which any human being can fight and never stop fighting . . . E.e. Cummings
This thing we call failure is not the falling down, but the staying down . . . Mary Pickford
Singing is the ultimate do-it-yourself activity. No one can do it for you and no one can make you feel good about the discouraging days. No one will get you to work on it tomorrow. Singing is your job. It's a test of will. But if you find this will, you will also find the voice of your dreams . . . Jeffrey Allen
Fate is being kind to me. Fate doesn't want me to be too famous too young . . . Duke Ellington
Learn from your very first steps to listen to, understand, and love the bitter truth about yourself. Find out who can tell you that truth. Talk of your art only with them and let them scold you to their heart's content . . . Constantin Stanislavsky

Practice/Rehearsal Tips
Where you practice can be as important to your vocal workout as how much you practice. Make sure you practice in a place where you feel free to sing out — without worry as to who might be listening.
Singing at gigs, recording sessions or band rehearsals should not be considered practice. You must also make time for yourself to sing without the pressure of having to sound good. Give yourself the luxury of taking chances and making mistakes during your own, private workout.
When you practice, do so slowly and give yourself the time to relax before your workout — don't rush! Haste is the #1 enemy of meaningful vocalizing.
If you vocalize for a half and hour everyday, you'll be surprised at how much more ready to sing you'll always be.
Always train yourself to be able to sing one or two notes higher than required in your performances. This insurance will allow you to relax on stage.

Physical Tips
The muscles used for sit-ups or leg lifts are the same used to support (or press) air through the cords to bring forth a singer's sound. Some of these exercises, on a regular basis, add power to your overall tone.
Your jaw should drop — as it does when you yawn — whenever holding a note in your upper range.
If you have to cough or clear your throat, do so gently. These actions are like sandpaper to your vocal cords.
Eat and sleep properly — and ideally — exercise daily. All of these things will enable your body to achieve a state of relaxation and vocal-cord readiness and will benefit your singing more than you'd think.
Maintain a high level of water in your body. The old adage eight glasses a day… Helps keep your vocal cords lubricated and conditioned.

Breathing Tips
The significance of the diaphragm as a muscle of breath support is over-emphasized by most music singing schools and teachers. The diaphragm has two jobs: it furnishes the power for inhalation and then controls tone support.
When you take a breath for singing — to open the throat — add a yawning feeling as you're about to produce the tone (the beginning of a yawn, to be exact).
Be sure the shoulders do not raise when taking a breath.
If you can hear your inhalation, you're taking in too much air or your stomach is tense. Be sure your stomach is relaxed before, and as, you inhale.
Always inhale gently when singing. Heavy gasping of air will tighten your throat.

Essential Tips
Posture is the foundation. Be sure your posture is erect when singing — not a military stance, but comfortably upright. This positions you for maximum support.
Always imagine the sound that you want to make and then sing it — using all resources available — your entire physical being, emotions, psyche and spirit.
A tight jaw is bad for good singing. Do whatever is necessary to relieve your jaw, neck and shoulders of tension before you sing.
Don't smoke. Smoking puts at risk the entire mechanism you're going to stake your claim to a vocal career upon.
Don't try to imitate another singer's voice. Discover your own, unique, vocal identity.

Good Luck.

Well, without knowing what your vocal range is, I can only recommend that you check YouTube for lessons. Kind of like this one: Https://www.youtube.com/watch?v=8VnuioNL…

You can learn all kinds of good tips and techniques on YouTube about singing.

The best way to start is to sing the best way you can and either have someone critique your voice or record yourself singing a song you know really well so you can compare yourself to the original vocals.

Another way I found is to play the video game Rock Band and turn the vocal volume down to where you can clearly hear your voice more than the original vocal track, but you can still make comparisons during.

Continuously doing this can help you to sing exactly like the original song and then slowly develop your own unique voice and make the song just that much more special to you.

Depending on the music you're trying to sing there are multiple methods for warm up:

Soft Rock/Alternative- Start with you lowest voice and slowly work your way to your highest voice holding the note. Continuously do this until you can do it without your voice cracking or breaking in the middle. Another way is to do the "Do Re Me Fa So La Ti Do" From low to high, then high to low doing it in reverse. This will make your voice smooth and harmonious

Hard Rock/Metal- If your trying to sing the gruff thrashing songs like Hatebreed or Slipknot, do everything above and you're all warmed up. Then get a hot cup of WATER. As hot as you can stand and drink it. Your throat will be burning, but unless it's scolding hot, it's not permanent. This must be water, nothing else. This will relax your vocal cords and make it extremely easier to growl and shout without completely tearing up your voice. Make sure that you completely consume all of the water so your throat is slightly dry and won't cool itself down with any of the remaining water.

Another method, one that I've used in the past, but wouldn't suggest doing too often is to use Vick's Soar Throat Spray or Dayquill and take a small sip. Open your throat up as wide as you can and take deep, rapid breaths until your throat is slightly numb. This also works with Cough Drops

(I don't condone doing the second method too often as it could mess up your stomach in the long run, however it is effective)

A third method is to cough really, really hard, like you clearing your throat until your throat is burning. This has the same affect as everything above, but I only use it when a hot cup of water or some Dayquill isn't availible. I suggest only doing this when nothing else is availible as it can mess up your throat.

For every other kind of singing technique, there's no special way to learn as the rest are similar to the two above. The more you sing, the more you can improve yourself vocally and be the kind of singer you want to be.