How to use anti static wrist strap when fixing iphone?

I'm changing the front and back glass of my iPhone 4. I have an anti-static wrist band but, what do I connect it to to ground it?

If at all possible, it should be connected to an earth ground,
a conductive work surface (conductive foam, steel, aluminium, copper, etc.),
and the ground bus of the phone.

At the absolute minimum, connect it to the sleeve contact of the headphone jack.