Popping noise, transmission leaked all fluid.

I have an automatic transmission. I was driving when there was a popping noise coming from the front of the car. The car then started to have the rpms go very high and not shift gears. I parked about 2 minutes later when I got to work. I came back to the car about 5 hours later and there was a lot of transmission fluid all over the ground. The engine is running fine and the shifter moves freely, but the transmission will not shift into any gear other than park. It was at night and I couldn't see where the leak is coming from and I haven't been back to the car yet. I don't know a lot about cars, but I'm guessing that it will not go into gear because there is no transmission fluid, and the problem is the leak I have. The car isn't worth doing any major repairs on, so if it is a minor repair I can do myself, any help would be appreciated. Thanks.