I recently bought a cheap road bike. I feel a little drag in the back. When I put it on a repair stand and turn the pedal, the wheel spins a few times and stops.
Could be as simple as the wheel rubbing on the brakes - rotate the pedals and listen for a scraping noise as the wheel contacts the pads. If this is the case, check that the wheel is true by observing for any wobble side to side as the wheel rotates. If that looks ok your brakes probably need adjusted away from the rims.
Start here for brake adjustment http://sheldonbrown.com/canti-direct.html#about but it very much depends on your particular brake type.
Wheel truing info can be found here - http://www.bikeradar.com/gear/article/workshop-truing-a-pair-of-wheels-19199/
If it's a cheap bike then my money is on the brakes rubbing.
Any brake should be able to be opened up or released so that it doesn't come near the rim. I'm assuming it's rim brakes and not disc brakes: a disc brake bike is unlikely to be what you'd call a cheap bike.
And when you spin the wheel, line your eye up with either one brake shoe, or part of the frame and see if the wheel itself is "true": that is if it's in line, or if it wobbles. A wheel that is out of true usually means a broken or loose spoke or two.
You can easily check the spokes by hand. They should all be about the same tension.
But no matter what, doing what you did is GREAT. Putting it up on the stand and spinning the wheel and asking questions (to yourself, to others) is the first step to learning about it, and then fixing it.