Check here for the correct timezone: http://en.wikipedia.org/wiki/List_of_tz_database_time_zones
SSH into the server
Run the following, with the relevant TZ database timezone. In this example, Europe/Londonln -sf /usr/share/zoneinfo/Europe/London /etc/localtime
Then, edit /ect/sysconfig/clocknano /etc/sysconfig/clock
Change the line to the correct TZ timezone:ZONE="Europe/London"
Save the file
Run to check all is now correct:date
Reboot the server