Thanks for posting. What email client would you like to import contacts from? Do you have your contacts in an Outlook address book or something like this? If so, you can export your contacts from that location and import them to Constant Contact directly or using an Excel file!
As for the Facebook friends, you won't be able to directly import these people as they have not given permission to be emailed. What we would suggest is installing the Join My Mailing list Facebook app so that your friends can subscribe there! Check out this FAQ for more detail.
Due to Constant Contacts strict permission guidelines the list of contacts you bring into your account would need to be people who have subscribed to your mailing list. We offer several ways to grow you list if that's what you are looking to do, check this out.
In real estate a way to get subscribers might be to offer your clients the option to signup when they come into the office or even when they are looking at listings online!