i have a 99 ford taurus se with 3.0 v6. It has bowed head gasket and why is gas getting in the water??

I would have to say this is easier than you might think, but I will try to explain it for you.
The cylinder where the head gasket is blown is most likely un able to fire the spark plug or the plug is fouled out. Since this is a fuel injected engine, the computer tells the fuel injector to shove fuel into the cylinder even though it isn’t firing. Now you have un burned gas in the cylinder and a blown headgasket which means it now has access to the cooling system ports. When the piston comes up on the compression stroke the unburned gas that is in the cylinder already can be pushed into the cooling system. Since the water pump is still moving the coolant around , the gas is now mixed in with the coolant and moved throughout the system.