First, you say hello and ask her how her day went. Tell her a little about how yours did. After you will go into a conversation. Just don't talk about boring things.
While this question is speaking obviously metaphorically, I'll give a more literal response: Be able to intelligently carry on your side of the conversation.
Hello.
sdsd
Try to bring sports in.
ask her to a movie or something.
no , but you shouldn't it's a invasion of privacy!
You can talk to them afterschool or even talk to her on the phone(if you have her ohone number).
You can have a conversation with a girl in the school backyard.
Tell her how much you enjoyed the conversation and tell her you look forward to seeing her...
For me, its always harder to talk over the phone then it is to text. Even to friends and family. If you want to engage in a conversation with a girl over the phone, always ask if she has unlimeted texting first. If she doesn't or YOU don't, try to make conversation with her face to face. If you are nervous, try making sure there are friends of yours arround. (trust me, its helps!)
It means she saw you, she is using a reason to bring up conversation with you. She's friendly.
Ask them how they are and what they were up to , then it should open the conversation up a bit - show and interest in her likes and dislikes.