Squid Issue

[Jeremy J. Swarm]

can someone help me configure squid? i get this error, and am a total
noob about what to do:

swarm at serverIke:~$ sudo squid
Password:
FATAL: Could not determine fully qualified hostname.  Please set
'visible_hostname'

Squid Cache (Version 2.5.STABLE12): Terminated abnormally.
CPU Usage: 0.008 seconds = 0.008 user + 0.000 sys
Maximum Resident Size: 0 KB
Page faults with physical i/o: 0
Aborted

Thx,
Screamin Ike