The main water valve won't open fully after I closed it. How do I shut off the water to replace it?
Call the local water municipality, they will be able to shut the water off either at the meter or before it. This is something that should not be done by a homeowner.

While you may find that you can access the main supply shut off you should not use it, as you could end up being fined by the city/town/county.  Also if you damage the shutoff or city/town/county water line, you could find yourself having to pay for the repair.