From Wiketomica

If you have the latest Eclipse (at least 4.5), you'll need to add CVS capabilities before you begin.

  • In the Eclipse menu, select Help -> Install new software
  • Select "Mars" from the dropdown menu near the top ("Work with:")
  • search for "CVS" (type filter text)
  • select "Eclipse CVS Client"
  • hit "Next" a couple times
  • accept license agreement
  • restart Eclipse