Ok here's the info I'm 12. 4"8 and 123 pounds I'm very overweight and feel horrible about myself. And my goal is 85 pounds. Please help.

You are way to young to "diet"
Cut out a good portion of junk food if you are eating it- have small portions at special occasions like bday parties.
If a lot of your calories are liquid- soda, sport drinks, coffee drinks, etc. switch to water.
Mostly increase activity. That is the most important thing.
Don't go on a special diet!!