1. Download the Neon Eclipse package using the below link

http://www.eclipse.org/downloads/packages/release/Neon/RC3

2. Go to Help –> Instal New Software.

3. Click “Add”.

4. Enter the information as below.

http://media.developerforce.com/force-ide/eclipse42

5. Click “Next”.

6. Accept the Agreement.

7. Click Finish.

8. Restart your Eclipse.

Cheers!!!