Found my birth mom

Hey guys so I need help. I am adopted and it was a close adoption so I had to wait till I was 18 to get in contact with my birth mom. Well here I am 5 months later after I turned 18 and feeling ready to get in contact with my birth mom. I just found her on Facebook 3 days ago and I’ve seen pictures of her and my little siblings including my older brother and his kids. Which makes me an aunt! But ... whenever I go to message her the only words that my fingers seem to type is just a hello. Obviously I’ve never done this so I’m a little stressed and overwhelmed but also very excited! I just can’t seem to get past the hello. So if anyone has been in my shoes or is going through something similar I would love to hear some stories or receive feedback on what I can do to go about this whole situation. Thank you for reading, it means a lot ❤️