Alright first go to Google and type in GIMP Brushes. A bunch of options will appear. Click on one of them that links to DeviantART. It should be the first option
-Step Two-
On DeviantART, there will be a search bar at the top. Type in "GIMP Grunge Brushes" Now find one that you like, and click on its picture. I chose this one:
As I circled, click download. A message will appear that will have three options, Open, Save and Cancel.
Click on save, and save it to somewhere you will find it easily (My documents, or My downloads). Name it grunge3
-Step Three-
Now go to START, My Computer, and find where you downloaded the brushes to. I downloaded mine to My Downloads.
Once you found where you saved it, you'll notice that beside its name there's a folder icon with a zipper on it. , right click on it so it kinda looks like the below image:
As you guessed, click on EXTRACT ALL... A window might appear, just hit extract. Another popup might appear, just close it, we won't need it.
-Step Four-
Now open up your GIMP program. Now click File>Prefrences. A popup will appear, and on the side there will be a series of folders. It looks like this:
Yes, click on the + beside FOLDERS. A bunch of other folders will appear, click on the one that is labelled BRUSHES.
-Step Five-
Click on the Icon that looks like a piece of paper :
Now this icon will highlight:
Click on that and find the brush file that you extracted (grunge3) and hit OK. a popup will appear telling you that you will have to restart the GIMP program before they appear. Restart your GIMP and they`ll be there!
If you want to download fonts, go to dafont.com and follow the same process, except go to FONTS in preferences.