It seems that converting time zones is a major problem for players here (with good reason). Luckily there are many tools out there to help us. One of those is timeanddate.com. This is especially handy since it provides a lot of services. Amongst those are Fixed Time and Time Zone Converter.
To use the first, simply go to this page, plot in the time in your local zone, click "Calculate fixed time" and post the link. Like this: 1pm GMT, 04/17-06. This can profitably be used when posting a (suggestion for a) time of meeting, for instance.
To use the latter, head over here, where you'll see a slightly different page. Here you'll be required to plot in the time and date you're converting from as well as the time zone converting to. Click "Convert time" and you'll have the desired time in your relevant time zone. This is mainly used in cases where the aforementioned service was not utilized, or when you're really bored and want to see what time it is on the other side of the World.
Editted for clarification.