Hi Mike.. Welcome to GTs.
I'd make sure the guitar has a good set-up..
An instructor, like Hunter says would be the best way, but I think I would want one that specializes in children and is checked out by your community.
This being said, fitting that bill maybe a hard trick. Also take a look at local public schools offering music classes. (group setting)
The lessons here at GT have no age rating and have tons of beginers lessons. The Core lessons has it all. GT can show her the right way.. Then as advanced as she may want to go.
A web search on line showed plenty of links. The link below has 9 free lesson. I seached (guitar basic for kids)
I'm not promoting this site, it just look simple to get from one point to another and also the first one I opened.
http://www.kidsguitarzone.com Hopefully this helps.