Applications may not open because they do not find the operating system they were expecting. Both the latest versions of PaintBrush and iPaint require Mac OS X 10.5 (Leopard) while the latest version of GIMP requires Mac OS X 10.6 (Snow Leopard).
There are older versions of the software available that support older versions of the Mac OS such as 10.4 (Tiger).
GIMP is an image editing program similar to Photoshop that can be downloaded for free at GIMP.org.
The GNU Image Manipulation Program can be downloaded from the downloads sections of GIMP's main website. Additional sources of GIMP on the internet includes CNet.
GIMP can be downloaded and run for free of their official website
To change the paintbrush color in GIMP, first select the Paintbrush tool from the toolbox or press "P" on your keyboard. Then, click on the foreground color box located at the bottom of the toolbox to open the color picker dialog. Choose your desired color and click "OK" to apply it. Now, your paintbrush will use the selected color for painting.
From what I can make of it, the Gimp Turtorials do no download with the GIMP program, but instead they prompt you to visit the website. In this tutorial it will teach you how to use the product.
Yes, GIMP is a freeware program.
gimp is free
The brushes should already come with the GIMP once downloaded. You don't have to download things separate.
It's a photoshop program.
It stands for: Gnu Image Manipulation Program
GIMP, a free image-editing program, can be downloaded at gimp.org. Just scroll about halfway down the page and click on the version of Windows or Mac that you have. The download should then start automatically. I recommend downloading it to your desktop so you can find it easily when you want to install it.
You can download it directly from the GIMP site.