I've seen a lot of questions about installing different things in Gimp, such as scripts, brushes, gradients, fonts, etc. So, now I'm here to help. I will be showing you how to install things in Windows.
Go to My Computer\Your Hard Drive (usually drive C)\Program Files\Gimp-2.0\share\gimp\2.0\
As you can see, you have different designated folders each item goes in. For brushes, paste them into the Brushes folder, for gradients, paste them into the Gradients folder, and so on.
Now, for fonts, they are different. You have to actually install the font on your computer for it to work. To do this, go to My Computer\Your Hard Drive (again, usually C)\WINDOWS\Fonts
Paste your font into the Fonts folder. You should see an install dialog pop up.
Make sure you restart Gimp so your new items will load.
With regards, Glider