Also please note, http://discussions.apple.com/ is the root level of Apple Support Communities
From there you can select your product. If you can't find your product, or where you purchased it from Apple it likely is not your forum.
If you have a Mac, go to Apple menu -> About This Mac to find your operating system if it is running Apple's operating system.
If you have a Mac with Microsoft's operating system, people in this forum may help:
Windows Software
If you have a Mac with a Server operating system, this forum may help:
Servers and Enterprise Software
If you purchased an App for your iPad, iPod Touch, or iPhone, this forum may help:
iOS Apps
If you purchased an App for your Mac, and used the Mac App Store and are having trouble, this forum may help:
Mac App Store
The iLife forum encompasses all applications iTunes, iPhoto, Garageband, iWork, iMovie and iDVD:
iLife
eBooks purchased for iPad, iPhone, iPod Touch are covered by:
iBooks for iOS