Ideas on starting a dm conversation with a girl? Answer and I'll answer 1 for you!?

There's a girl I'm friends with on Facebook and instagram and I think she's really cute. We went to the same community college together (her a year behind me) but never met. I'm now at a university and she's doing online classes for a separate university (I know from what she puts on Facebook). I want to start messaging her, but don't exactly know the best way besides hey and thats not creative nor do I think would make someone interested in a conversation. I also thought about talking about not realizing we went to the same community college but I'm not sure again. Do you have any ideas?