How do you message a girl after knowing someone's insta id? I am not sure how my first few messages should be like for starting the convo?

I M21 met a girl at my office, had short conversations and we exchanged our ids, I am interested to know her so like maybe take her to cafe and get to know more about her. Actually I dont know the next steps because I have never dated anyone before. And yeah I seriously dont know if she's interested in me.