You fill it until the fuel comes out the top of the pump. That's why I said to clean the area around it: so dirt does not go in when you fill it, or float into the pump once the fuel is flowing out.
If your pump is bone dry, it should take about 1/2 quart to fill it back up again.
Once you've got fuel pouring out of the top of the pump,out of the return hole, put it all back together and crank it over. It won't want to start right away, but keep cranking until it fires. Or, you can crack the injector lines until the air comes out, and then re-tighten and crank. It takes about as long either way, but if you don't loosen the injector lines, you have less fuel spilled in your engine bay.