Leaking water heater

Hi, I just noticed that the hot water heater is leaking, and it's leaking a lot.
It's a Reliance Sta-Kleen 805, and gas. The leak appears to be coming form the bottom.
I don't know what to do. My husband is at work and today he forgot his cell phone, but he's not too much of a handy man, and I can't get a hold of my mom.
Do I shut off the water? And if I should do that, how would I find that?

There should be 2 pipes attached on the top (in most cases) of the water heater. They will be labeled hot and cold or, have red and blue markings. Follow the cold or, blue back to the valve and turn it off. Next you need to turn off the water heater. Down low on the side there is a gas valve turn it to the off position.

You probably will need a plumber to replace it if the tank is leaking.
I would recommend replacing it with a Bradford-White Water Heater.
Whatever you do avoid Whirlpool and A.O. Smith.

It's probably a good idea to shut of both the water and the gas supply to it.

There is a knob on the WH, which usually has three positions: ON, PILOT, and OFF. To get it to go to off, you usually have to press down on it while turning.

Usually, but not always, there's a shutoff valve on the cold pipe comiing into the WH. You can tell which is which if you carefully touch them...especially if you have a faucet running to get hot water...one will be cold and the other hot. If you have a shutoff, turn that off AFTER you turn the gas off. You don't want the tank leaking and the gas still on.

Then, if there is a good place where you could drain some water, and you have a hose, you could hook up a hose to the drain valve near the bottom of the WH. It may have a bunch of sediment in it, so it might not actually drain through there, but try it. Run the hose somewhere it can drain by gravity, then open the drain valve. If you open a faucet on hot somewhere in the house, the tank will drain. That's probably better than slowly dumping it on the floor around the tank. If you can't run the hose somewhere, just shut the water and gas off going in, then you won't get a constant flow out of it. Depending on the size of the leak, you still could get 40 or more gallons on the floor, so draining it away has advantages.

Next time, consider putting an emergency drain pan under the new WH, it will contain and channel the runoff to a drain somewhere.

Now, if the water is leaking from the valve on the top of the heater, and coming out of the pipe directed towards the bottom, you might just need a new valve. Often, you can put a pail under that discharge. But, if it's coming from the actual tank, the tank is shot...time for a new one.