how do I enable the root user from the Directory Utility?

How do I enable the root account? I don't see any options related the system user. Do I enter the server as "localhost"?

What do I select here?

System Software Overview:

  System Version:   OS X 10.10.2 (14C1510)
  Kernel Version:   Darwin 14.1.0
  Boot Volume:  Mac OSx
  Boot Mode:    Normal
  Computer Name:    Darren’s MacBook Pro
  User Name:    thufir (thufir)
  Secure Virtual Memory:    Enabled
  Time since boot:  1:03


Hardware Overview:

  Model Name:   MacBook Pro
  Model Identifier: MacBookPro9,1
  Processor Name:   Intel Core i7
  Processor Speed:  2.3 GHz
  Number of Processors: 1
  Total Number of Cores:    4
  L2 Cache (per Core):  256 KB
  L3 Cache: 6 MB
  Memory:   4 GB
  Boot ROM Version: MBP91.00D3.B08
  SMC Version (system): 2.1f175
  Serial Number (system):   C02HH5JQDV33
  Hardware UUID:    FBB1FF0A-6EAC-5423-9E8F-405B181EF5F3
  Sudden Motion Sensor:
  State:    Enabled