How to make a difference in the world?

[ella]

I'm a 16 year old girl living in the US and I've always wanted to do something to help as cliche as that sounds. I always get bits of ideas but can never formulate an entire idea that makes sense. Right now I have some ideas but I don't know what I could do with it. That's what I need help with. I was thinking of starting some sort of fundraiser for something, but on a global scale. The method I was thinking of doing it is very "old-fashioned" in a way and I know I'm missing some details...which is why I'm asking on here. My plan was to get people from around the US, Canada, and Europe (I can find people online very easily through forums and stuff. I've met so many people that way) and get them to join in with me. Then after I get some people, we can communicate with each other and create a poster like thing which I was thinking each of us could stick onto those wooden electric poles. The poster would have a website on it(I'd make it before hand) with information about the thing and then there'd be more people joined in with the "movement". I have a couple questions:
1. Would this work? *Answer follow questions if it's possible to work*
2. How many people should I get at the beginning?
3. What should be on the posters?
4. What should be on the website?
5. What should the movement/fundraiser be for?

Any other tips or suggestions?

Thanks in advance!