Do it the same way we start kids riding. Remove the pedals, and lower the seat so she can get her feet on the ground. Then go to a place where she can use it as a strider bike. Once she is whizzing around with reasonable balance, replace the pedals. She will take off with confidence and a smile on her face. As her confidence grows, the seat can be raised to a more efficient riding height.
Get her a helmet!
Glide Bikes, Balance Bike, Push Bike for Kids - GlideBikes.com
https://www.youtube.com/watch?v=fgsyILemn2E