There is a link to the bug reports section on the main page of the forum. There is a sticky thread in the bug report section detailing how to make a bug report, including the format to use so that all the relevant information is included. It's easy enough to follow, but sadly people join up, rush in instead of checking the sticky and don't provide their details, then ignore the requests for more information - hard to fix the bug if they don't have all the facts. The more information they have, the faster things get fixed.
They don't expect players to be bug testers either, but just like a