You can check for updates in two ways:
Use Help / Check for Updates
This option checks for updates of all installed Eclipse features, and contacts all available update sites. This action is easy to invoke, but for some users this action takes a long time to complete.
Use Help / Install New Software
This is the same action as used to install new features, but can also be used for updating. Use this action if the first option takes a long time or does not complete.
In both cases, you will see Reactive Blocks listed in case there are updates:
Eclipse has an option to check automatically for updates in the background, which you can enable in the preferences:
Open the preferences and look which is the current version.