The Force.com IDE installs into Eclipse using the built-in Install/Update wizard.
1. Launch Eclipse, and then click Help > Software Updates > Find and Install.
2. Select "Search for new features to install" and click "Next".
3. Add the Force.com IDE Remote Site:
- Click "New Remote Site". The New Update Site dialog opens.
- Set the Name to "Force.com IDE" and the URL to http://www.adnsandbox.com/tools/ide/install/", then click OK.
- Select “Europa Discovery Site” and "Automatically select mirrors”, then click “Finish”. Eclipse will search the selected sites for the required plugins.