If Attributes or Behaviors is greyed out, it is because the master segment was created without either an Attribute or Behavior table specified.
Adding Profile Behaviors
After creating a batch or real-time segment, select Add Behavior from under Profile Behaviors:
Use all or any drop down to indicate whether a segment matches all or any of the specified attributes, behaviors, or existing segments.
Define a new rule or select the Add Rule link.
Make selections as necessary for your behavior rule.
Save your changes.