Like Gary said, the forum stores info on you when you post etc, and this is the starting point for forum owners/mods. Forum mods and admins usually have access to this info, as well as tools that can trace people. Using simple methods, I could get some of that info without hacking or anything. Just asking you to click on a simple link would give me your IP, location, ISP, browser, OS and what ever else. Then it's just a matter of time checking out the info, and cross referencing it. There is no illegal hacking, emailing, or downloading of exe files that would track you. Just simple internet tools and time looking.
The people that pray on kids on the net, spend time building up a profile of the child (grooming them). They gather little snippets of info here and there, and prompt them for more. Then when they have enough info, they make their move. I know of many kids that put a photo of themselves on an MSN profile, as well as their location. This is just an open invitation to the filth that roam the net.
PS: You have already told this forum your rough location, plus given clues that could narrow that area down. And that's in just 3 posts
and no searching.