There is a package called eclipse-cdt in the Ubuntu 12.10 repositories, this is what you want. If you haven't got g++ already, you need to install that as well, so all you need is:
sudo apt-get install eclipse eclipse-cdt g++
Whether you messed up your system with your previous installation attempts depends heavily on how you did it. If you did it the safe way for trying out new packages not from repositories (i.e., only installed in your home folder, no sudos blindly copied from installation manuals...) you're definitely fine. Otherwise, you may well have thousands of stray files all over your file system now. In that case, run all uninstall scripts you can find for the things you installed, then install using apt-get and hope for the best.