We bought a house that was winterized but there is not hot water. Is there something we need to do to the water heater to make it start back up again?

For starters, the circuit breaker on and the inlet valve open? (Tap the tank to see if it sounds empty or open the valve at the very bottom to see if water comes out.)

When we turn water back on to a home after winterization, we make sure the drain is closed, open the shut off valve on top of the water heater, open a hot faucet and leave it open until a good stream of water and no air is coming out of the fuacet, then shut the fuacet off. Then and only then do you turn the breaker on for the water heater. If the breaker was turned on before the tank was filled with water, the elements in the water heater would have burned out.