What should I do now?

I finally got a break and got this girls number. I got so lucky to be able to sit with her during a test because someone else took my regular seat. After we walked out at the same time and we both walked to the computer lab. We didn't say much though and this was the first time i talked to her. I just asked her how she did on the test. I then made up an excuse to get her number. I told her i was going out of town and tht i needed her number just incase so i shouldnt be texting her tht i like her yet. She gave a little smile after tht and i was gonna say wat are u smiling at but i didnt wanna risk it and i said thanks and left on tht note. What's the next step now? i want to text her to get to know her but not get annoying. My goal is to ask her out to a movie eventually.