It's very easy to change that orange theme that usually accompanies Ubuntu
Many Ubuntu users complain about the orange color used in operating systems made by Canonical, but that can be easily rectified with some themes.If you like Ambiance or Radiance, the two themes are usually shipped with Ubuntu, and you don't want to give them up, you can change the way your system looks with just a few themes. The solution is called the Ambiance & Radiance Colors Suite and it's a package that contains many color variants of the two default themes in Ubuntu.
The installation is quite simple and all you have to do is to add a PPA to the system and enter a few commands. It's really nothing to it. Open a terminal and paste the following commands (you will have to be root in order for this to work):
sudo add-apt-repository ppa:ravefinity-project/ppa
sudo apt-get update
sudo apt-get install ambiance-colors radiance-colors
Now you will also have to activate them. This can be easily done with Unity Tweak Tool, which can be found in the official repositories. In the same terminal, enter this command:
sudo apt-get install unity-tweak-tool
Start the application and look for the Themes button. From there, you can use a number of different colors for your favorite Ambiance or Radiance themes.