Before you can start developing, you have to setup Eclipse. Your first need to install Eclipse Galileo with C/C++ support. The easiest way to do this is to download "Eclipse IDE for C/C++ Developers" from http://www.eclipse.org/downloads/. You can of course use an already installed copy of Eclipse.

The following plugins have to be installed:

• Eclipse C/C++ Remote Launch
• Remote System Explorer End-User Runtime
• Remote System Explorer User Actions
• Target Management Terminal

Eclipse - Menu Help -> Install New Software...

In the following dialog, chose "Galileo - ..." for "Work with:" as shown in the screenshot and select the needed plugins.
Eclipse - Install plugins

Now Always choose "Next" and accept the license, when your asked to do so. In the last dialog click "Finish" an wait for the plugins to be installed. After that, restart Eclipse.

If you also want to use the serial terminal from inside Eclipse, it is also needed to install the RXTX library. This can also be done via the Eclipse install dialog. The RXTX library is not part of the standard repositories so you have to add an additional site.
Eclipse - Add RXTX site

After that select the "RXTX - End User Runtime" and proceed as with the other plugins.
Eclipse - Install RXTX

Now, all needed plugins are installed.