it depends on your distribution. If it's redhat, mandrake, SuSE, generally speaking you'll need to get packages from www.gnome.org,
or get an update from those companies. With debian, you just update when debian releases them. Dropline is for slackware, so if you have slack, you can use that.
Basically, if you're a newbie, you probably shouldn't worry about updating your desktop yet. Learn to use the system, then when you've acquired enough skills and knowledge, you'll know. Until then, comfort yourself in the fact that while there are "neat" things in the new version, a desktop is nothing more than a way to start programs.