Hey there mariepiers,
It sounds like you are having issues signing into your FaceTime account on your Mac. I would use the troubleshooting from the following article to help with this issue:
FaceTime for Mac: Troubleshooting FaceTime
http://support.apple.com/kb/ts4185
Use your Apple ID to register and use FaceTime. FaceTime registration validates your Apple ID and email address for use with FaceTime.
If you are unable to activate FaceTime, try the following:
Sign in to FaceTime for Mac using a valid Apple ID. After you validate the email address for use with FaceTime, other FaceTime users can connect to you using that email address. If you encounter issues registering or using an Apple ID account:
You can make FaceTime calls using the FaceTime app. You can call FaceTime users whose contact information is in Contacts. You can add contacts and edit contact information in either FaceTime or Contacts. To place a video call, you may use a phone number or email address.If you encounter issues making or receiving FaceTime calls, try the following:
- Verify that FaceTime is enabled in FaceTime > Preferences.
If the issue persists, or if you see the message "Waiting for Activation", try toggling FaceTime off and then on.
- Verify that the Date, Time, and Time Zone are set correctly:
- From the Apple () menu, choose System Preferences > Date & Time > Date & Time.
- Enable "Set Automatically".
- Click the Time Zone tab and confirm the closest city is correct.
- Verify that both parties are connected to an active broadband Internet connection.
- Verify the phone number or email address being used is the correct one activated for FaceTime.
You can verify that you are using a valid Apple ID at appleid.apple.com. You can also create an Apple ID or reset your password from this website.
- Verify that both parties have installed the latest software updates for their Mac and/or device. See:
Thank you for using Apple Support Communities.
All the very best,
Sterling