I'm guessing that you have bought the tree already, is that right ?.
If so I'm hoping that you have purchased a 'pot grown' tree rather that a potted tree. The latter may have been dug up from a plantation, with it's roots exposed to the elements, then possibly days later, shoved into a pot with some compost or soil and then offered for sale.
If you have a pot grown tree then obviously you will stand a much better chance of keeping the tree alive for next year and maybe more.
The best advice I can give, is keep the tree moist and away from radiators or any heat source.
Put it outside as soon as possible, after the festivities then continue to look after it by keeping it weed free and watered. one way of preventing it from drying out is to put a tray under the pot.
Re-pot it in the spring with a soils based compost, and with luck, you're tree will last for many years to come!
Good Luck Chip