Unfortunately, not everyone that you know will think that being a lesbian is the greatest thing since sliced break. It's hard to know who can handle the information and give you support. Some friends may accept you. Some may turn away from you or tell other people without your permission. Telling family can be very difficult.
Some families are very supportive.
But some lesbian and gay youth have been kicked out of their homes when their parents found out. Maybe there's a guidance counselor or social worker at your school, or in a local youth or counseling agency, that you can trust. It's important to have someone to talk to because it's not normal or healthy for young people to have to keep secret such an important part of their lives. First I would ask myself if I felt ready. Then I would talk to my partner to see if she felt ready.