You can easily export specific contacts, or all your contacts by doing the following:
Go to Manage Leads/Contacts.
Filter your contacts as needed. If you don't filter any contacts, then all contacts will be exported.
Click on the checkbox to select All Contacts.
Click on Perform Action.
Click to Export Contacts.
Follow Onscreen Instructions to Export your contacts.
You'll now have the opportunity to download a .csv file with your contacts.