GIMP DESCRIPTION

Apart Paint or Picassa, there is a software called GIMP that can also manipulate graphics and images. Gimp 
runs on Windows-based systems and is a free and open source image editor that provides small businesses with a free and easy way to  edit photos and author images. GIMP features include a gradient editor, blend tool and anti-aliasing.

 GIMP also offers complete manipulation tools for rotating, cropping, scaling, a foreground extraction tool, and multiple selection tools. The GIMP website provides visual tutorials, and a registry of plug-ins, scripts, and images that the development community have contributed to help you get started

You can download GIMP in some webpages like: http://www.gimp.org/  ( main one)

and here you can download the GIMP portable app: http://portableapps.com/apps/graphics_pictures/gimp_portable