Most schools have a guidance office they can go to. Encourage the student to visit the office and speak to someone there, as they're probably trained to deal with these things.
If there's no such office, the child can ask the school office for help - they can go to the secretaries and ask to talk to the principal or someone. If they don't want to tell the secretaries what it's about, just say that it's a personal issue, etc. Make sure the kid knows that they aren't obliged to tell the secretaries if they don't want to.
Otherwise just have the kid talk to any adult teacher they're comfortable with. The teacher can direct them to the appropriate person to talk to.
If all those options fail, provide the Kid's Help phone telephone number (google it).
