She probably didn't take it seriously. But if you went up to her and started hitting on her obviously, she might think that it may have been something.
But since she obviously doens't know you that well, I woudl say get to kinow her. Go up to her. Go "Hey, my name is blah blah. I notice we're in the same whatever class together." and start talking.
>>9's right. Don't take her seriously. This is your first time and it would be a terrible mistake to take it seriously. If you do, you're just gonna end up looking desparate and not only that, you'll probably get hurt. So take it as practice.