This is a lost art - do not close the big valves at the bottom of the radiator check keep it wide open . first put the smallest valve you can get for the space the thermostat is in and adj the
heat anticipator on the round thermostat for steam heat ( directions with thermostat ) .
As you move away from the furnace you put bigger valves on the radiators . You may get to the point where the rooms farther away still dont work . Take the valve out completely just leave the hole open -and run the furnace by turning up the thermostat - If the radiator heats up you need
more venting - scew in a straight fitting - screw
a Tee fitting onto that and 2 big valves onto the Tee . But remember the smallest valve at thermostat- and the heat anticipator set right before you do anything !!! let me know how you make out