Here is a guide for testing water heater elements:
 

Water heater elements all have different voltages and wattage. Using Ohm's Law you can calculate cold resistance of a water heater element. Divide your wattage by the voltage the heater is using and this will get you cold resistance. If the tank is still hot or warm this can affect your readings a bit. So, its best to let the tank cool as much as possible before taking a reading. In general, anything between 5-25 ohms is still deemed as good.

Note: On a new water heater, a burned out upper heating element is almost always caused by turning the power on before the tank was completely full of water (dry fire).

Start the process by shutting off power to heater. Disconnect leads going to the element. Set your meter to ohms and measure across the two screws and record your reading. Make your decision as to weather they need to be changed out or not.