It is minus 6 hours. Just remember that noon on Eastern time zone would be 11:00am Central. That is the easiest way to remember plus or minus.
If you google "UTC" and look at "US Time Clock" you would end up with this link:
http://www.time.gov/timezone.cgi?UTC/s/0/java
That link should give you the time at GMT. Then on the left is a button saying something to the effect of "Change Time Zone" that you can click on and then choose the appropriate time zone.
I use this site every time we change to or from daylight savings time to make sure my watch is set right.
Terry