Follow these steps to locate, install, and configure Mars Eclipse:
Locate the Mars Download: Open a browser and go to http://www.eclipse.org/mars/.
Download the Tarball: Click the "Download" button and then use the "Linux for Eclipse IDE for C++ Developers" appropriate for your development system (e.g. 64-bit under Linux for Eclipse IDE for C++ Developers if your development system is a Linux 64-bit machine.
Unpack the Tarball: Move to a clean directory and unpack the tarball. Here is an example:
$ cd ~ $ tar -xzvf ~/Downloads/eclipse-cpp-mars-2-linux-gtk-x86_64.tar.gz
Everything unpacks into a folder named "Eclipse".
Launch Eclipse: Double click the "Eclipse" file in the folder to launch Eclipse.