Help to work on Gazebo 5.0 for a newbie in Simulation

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There are a number of threads explaining exactly this. I would recommend only diverting from default package configurations if you are really missing something. Having 2 versions of ROS will probably complicate things if you're just starting to learn.

If you don't need Gazebo5, simply install Indigo which includes Gazebo2 with sudo apt-get install ros-indigo-desktop-full.

If you really need Gazebo5, do the same (install ROS Indigo) and then remove gazebo2 and install gazebo5 and gazebo5 wrappers. Check this thread: http://answers.gazebosim.org/question/8598/how-to-install-ros-indigo-gazebo-ros-control-with/. There's an official page as well but this one doesn't include any step by step manual; it's here: http://answers.gazebosim.org/question/8598/how-to-install-ros-indigo-gazebo-ros-control-with/

As for understanding the beginner tutorials, the step after installation in the tutorials is Getting Started, did you follow that and then continue on to Build a Robot? Maybe you can be more clear on what you don't understand or what you plan to achieve?