You are now ready to log into the GUI (Graphical User Interface) of FreeNAS.
Using your regular PC (i.e. not the server now), open a web browser (e.g. Firefox).
This should bring up the login screen.
The username is admin and password is freenas. Enter these details and log in.
You should see the System Status page as below:
If this works, you are now free to make the server PC headless by disconnecting the keyboard, mouse and monitor, since these are no longer required, and merely taking valuable electricity. Consider turning off unnecessary hardware from the server PC BIOS too; audio, floppy drive and CD/DVD drive controllers are all unnecessary at this stage. Remember to leave USB support on though!
Time to change the default username now.
Ref: Daily Cup of Tech