Miley Cyrus raised awareness about disadvantaged youth by having a young homeless man accept her VMA award on Sunday night -- and now she's upping the ante by trying to raise big bucks for the cause.

Miley used the ceremony as the launching point for her campaign to support the Los Angeles-based My Friend's Place -- a service center that helps young homeless people regroup and build self-sufficient lives. She tells Ryan Seacrest she's been working with the group for a while, but thought she'd go public after seeing how much the press watches her every move. Miley says, "If I am going to be given this loud of a voice and this huge an opportunity to talk to young people in America right now, I want to see what positive I can get them to take in and get involved."

To help that along, she's initiated a Facebook outreach asking for donations -- and anyone who gives $5 or more will be entered into a contest for an all-expenses-paid trip to Rio de Janiero for a concert and meet-and-greet at the end of September.