is there a trick to turn the water off to your house?

It should be a two minute job once you know where the valve is. Normally it's where the supply pipe comes into the house - under the kitchen sink is common in older homes, or by the meter, or in a basement or utility area. There's often a second one at the boundary, under a small cover in the pavement. Turn clockwise to close. If it's stiff, don't force it with a big wrench, old valves can snap. Worth finding it now and testing it before you actually need it in a hurry.