Your little tree is a cultivator of Korean Fir - it can handle temperatures to Zone 5. But, as you realized, not in a pot (good observation). The pot decreases the hardiness by 2 zones. I don't know what zone you are.
The vendor misled you by telling you to water only after the tree was very dry as firs need to be constantly moist (not wet but damp).
To determine if your tree is still alive: Is it losing needles? Do the branches snap off when you bend them? If you can find a bare spot on the trunk, scratch it with your fingernail. If it is green under the top layer of bark, the tree is alive. If its brown or hard, the tree is dead.
If its still alive, pick a spot for it to live and read up on the care:
Korean fir 'Kohout's Ice Breaker'
If you choose to keep your tree indoors for the winter, find a cold spot (do you have an unheated shed, basement or garage with a window?), the heat in your house will kill it. Remember to water.
