Please help us to create new ideas for a charity campaigne.?

Okay, so we are creating a charity campaigne and we are only highschoolers. To begin our campaigne we want to creat something small just to spread the word on who we actually are and our main goal. We are planning to do a mini event that isn't over the top. Can anyone suggest things we can do just for starters? Remmember we need an event that is not to big and that can be helpful for charity. Something knew and outside the box.