Here is an easy tutorial:
1. Download ZIP file http://bit.ly/ColorfulSidebar and expand it.
2. Install SIMBL from the expanded folder.
3. Move the ColorfulSidebar.bundle into the following SIMBL plugin folder:
4. Restart the Finder through the Terminal:
$ cd /Library/Application\ Support/SIMBL/Plugins
uki:Plugins uki$ ls
ColorfulSidebar.bundle
4. Restart the Finder through the Terminal:
$ killall Finder
This is an edited post from original article by Natalia on CyberWalkAbout.com