Now that you know how to reach someone, consider what you want to say. It doesn't have to be something fancy or lengthy; rather, anything brief and sweet will suffice. A simple "Hello, my name is _____, and I'm excited to be your roommate." would suffice. If you have any questions or concerns about living with another person, such as whether or not they'll be quiet during night hours, then feel free to ask them directly. If you're still unsure about what to say, then simply send a gift. Personalized gifts are always the most effective, such as a photo album or map of the area where they live so they can get to know their neighbors. You could also send fruit or vegetables if you know they like green things! Gifts shouldn't cost a lot, so look around your house or find other cheap options. No matter what you choose, make sure it says "Happy Birthday" on it!