You first need to add the new release's repository as follows:.
To upgrade Eclipse IDE to the next major release Upgrading existing Eclipse IDE and Installed Features to newer release 6.3 Upgrading from Europa (3.3) and below.6.1 Upgrading from previous versions to Neon (4.6) is NOT supported.3 Beta-testing milestones and release candidates.1 Upgrading existing Eclipse IDE and Installed Features to newer release.