Yeah, you can learn.... if you don't mind a couple of weeks with a badly broken ankle with a long time of rehab.
You can NOT and I repeat, NOT go up onto your toes without proper ballet training. You just can't! It's a very stupid and foolish thing to do. Not to mention that there's no joy or fun in it unless you know what you're doing. Unless you want to live your life with possibly permanently ruined feet from trying to do this without training, then I highly advise you don't try this.
Us ballet dancers train for YEARS on end in order to stand up en pointe. Most of us take at least 3 ballet classes a week for a minimum of 3 years or more along with a pre-pointe class before we're allowed to go up onto pointe.You have have to be done growing, have strong ballet technique and be physically strong enough to be allowed to go up onto pointe. As I like to say, if you can't do it in flat shoes, then by no means will you be able to manage it en pointe!
Cheer leading training is NOT ballet and will not help you with your pointe attempt. You need mainly strength not flexibility for pointe. It doesn't matter if you think you can balance well either. You aren't a professionally trained ballet teacher. What you think you know doesn't mean you're right.
Many people with little or no ballet training want to try pointe because it looks fun or impressive. I'll tell you now, it's neither if you don't know what you're doing. No one will be impressed by someone staggering around like a drunk dancer on their toes, and it's not fun if you can't manage it either.
If you want pointe that badly, take real ballet lessons for a few years and then reconsider. Or, you could not listen at all and think "I'll prove them wrong, I don't need ballet training!" and go right ahead.
It's your own choice. We can't stop you. However you'll regret it once you hurt yourself. A sprained ankle would be mild. However I have heard horror stories of kids getting pins in their ankles after they've just stood up, lost their balance after letting go of the chair and falling right over.
I highly suggest again that you reconsider. Sorry if I sound like i'm being incredibly harsh to you, but i'm trying to spread the truth and prevent anyone from doing stupid things that could cause permanent damage later on.
Hope I helped.