Things required:
Winzip
http://www.deviantart.com/Step by Step
1. Find a GIMP brush. If you find one, download it. Be sure it's a zip. file.
2. Then click the download tab below.
3. Them a Winzip will appear in your computer. Click "Use Evaluation Version".
4. Then you will see a folder (ex:Gimp Brush Name), double click it.
5. Then, you will see a list of brush names. right click, then click "Select All"
6. Go to tools>Unzip and try.
7. A CheckOut box will pop out. Click "OK"
8. Now, you will see the list of brushes on the Winzip folder shown in your normal folder. Copy them all.
9. Go to YourFolder>.gimp-2.6>brushes
10. Right click>>paste
11. Check out your GIMP, if the brush didn't show up, try changing the rule "Paste" into "Paste Shortcut".