How do i tell someone i think have depression and may be suicidal im 12?

They most likely have issues of their own or they just really don't have a life at all. If you don't look like they bother you then they might try to find a new target. But do not try to commit suicide because it would be the dumbest thing you ever did. I did and all's that happened was I ended up in a hospital for four day and like everybody quickly knew and then I had to go to a mental hospital for 7 days which really didn't do anything.