My refrigerator is not cooling. It's new.What could be wrong?

If it's new it is under warranty. You should do no more than call for warranty service. Any tampering on your part could void warranty

Assuming that there is electric power to the fridge, does it have a fan? If so, does the fan turn on?
Have you checked the temperature setting? Make sure it's not set to OFF.
If you have checked these things, definitely call for warranty service!