what did you install in the first place ?
Eclipse IDE for C/C++ Developers
Eclipse IDE for Java Developers
the older "Eclipse Classic 4.2.2"
the major distros have eclipse in their repos
yum install eclipse
apt-get install eclipse
or did you use the file from the eclipse web page
if so read the install instructions
--- install guide ---
--- nix users --
it is normally best to use the one that is in your distros software repos
as that one is configured for your operating system