Do you want to export your contacts from Yahoo Mail?
First, in the left side navigation, click Contacts:
Then, click the box to select all contacts, then click Action -> Export:
The export file can be saved as a backup that can be imported to Yahoo, or used to migrate your contacts to a new email service provider such as Outlook.com
Over 2 million online accounts were recently compromised before the service outage started.
If you suspect your account was compromised (well, even if you don't) please follow this guide too to make sure you have the latest recommended security settings and that your account information is correct and up to date: