How to train?

What commands does she know? I'm assuming the basics like come and sit and down?

The way we teach it is to have them sit, tell them to stay and then step directly in front of them so your legs are almost touching them. Keep praising as long as they stay and release them after a few seconds with great fanfare and a treat. Keep extending the time until they'll sit there for a minute while you're still right there to correct them immediately if they get up.

Then start going further away. At first just a step, then a few feet, then further and then practice leaving the room and coming back.

It's worked pretty well.