The elder said to introduce a girlfriend and gave me a mobile phone number to contact myself. How to send the first text message? She knows I exist.

First of all, aside from the question of what to say, I think you should know what kind of mentality to face this upcoming love. Of course, the beginning of a relationship always makes people feel nervous, but I think, no matter what, you should give each other a true self and be honest in language. As for what to say, of course, it is what you want to say most. If you want to fall in love with her, you might as well speak your mind directly and don't care about any old-fashioned questions. Say whatever you want, such as "Hello, I'm XXX. After listening to the introduction of my elders, I really want to meet you. Do you have a minute? Maybe we can have dinner together tonight and get to know each other. Of course, whether we can be together depends on what you mean. " Hehe, the above paragraph is what I would say if I were you. If you think it is good, you can adopt it. In short, just say what you want to say sincerely and boldly. Remember, be confident!