Well that 1 month ago did she tell you in private? Cause it depends if the girl is shy about her feelings, wouldn't it be ackward for you to tell her in truth or dare not knowing if she likes your or not with a couple people watching. To tell if she likes you, talk to her on msn or the phone. Maybe talk to one of her best friends, if she might tell you. It always depends on the girl and how she like expresses her feelings.
Edit: Oh wow didn't know you were 10 Then yeah just listen to what Sky said.