When a 23-year-old man contacted her through an online forum, she hadn't thought age was an issue. She had preferred to believe the best in him.

The man had said he found her online profile interesting and invited her to join a group. But to do so, she had to earn his trust.

And the only way she could do so was to send him inappropriate photographs of herself.

While she had initially thought it a bad idea, the man persuaded her it was ''just skin''. She sent him a photo she didn't think revealed much.

The man convinced her to meet him. After all, by demanding she earn his trust, he, himself, seemed trustworthy.

The week after Sage met the man, two Australian Federal Police agents arrived at her door to interview her about the man. They said he had been arrested and charged with child sex offences. He has since been jailed.

Sage, who is now 17, shared her story at a ceremony in Canberra yesterday to mark White Balloon Day as part of National Child Protection Week.

Among those to attend the ceremony at the National Museum of Australia were federal Home Affairs Minister Brendan O'Connor, ACT Minister for Children and Young People Joy Burch, and the ACT's Chief Police Officer, Assistant Commissioner Roman Quaedvlieg.

Mr O'Connor later launched an online video featuring students from Canberra's Daramalan College designed to alert young people to the dangers of ''sexting'' the distribution of personal and sexual images through mobile technologies.

White Balloon Day was established by child protection advocacy group Bravehearts to highlight child sexual assault in Australia. The theme for this year's day was ''Help us help our children''.

Sage told The Canberra Times she had made a mistake and it was a stage in her life from which she had since moved on.

''And I'm happy that it didn't affect me as badly as it could have,'' she said, adding she had the AFP to thank for that.

She said teenagers had to be aware online predators were charming and manipulative. It was second nature for them to ''twist and use people to their own advantage''.

For more on this story, including Sage's advice on dealing with strangers met online, see the print edition of today's Canberra Times.