You should say this:
You: Hey, you're Celia...right?
*Wait for her to answer*
You: Oh, okay! You know, I was wondering if we could keep in touch. Talk during lunch or something like that. Maybe we can become friends! You seem like a really lovely person.
*Then the conversation just kind of runs it's course*
You - Closing: Okay! It was nice to talk to you. I hope to nice chat like this one with you again.