On August 2, Instagram launched Instagram Stories , a new feature that lets you upload a photo or video, overlay it with doodles or text, and share it with your followers until it expires after 24 hours. But the launch wasn't truly complete until Kate Middleton got on board.At last, the Duchess of Cambridge has appeared in her first Instagram Story, Vanity Fair reported. The story, shared by Kensington Palace Wednesday morning, shows Kate and Prince William at a charity event in Luton, England.The event celebrated the reopening of Bute Mills, which houses the charity Youthscape . Youthscape offers a variety of services to young people, according to People . This includes mental health services, a cause near and dear to the royal family's heart.In fact, Kate and William participated in a number of events related to mental health Wednesday. They're supporting a project by the organization CHUMS that helps young people affected by suicide, as well as one by Our Minds Matter (OMM) and the Luton Council of Faiths and Grassroots that fights the stigma associated with mental illness.It's a jam-packed day for Kate, but it also sounds well worth it.