Sectors on Terrain and other objects

Unity Engine
1

How to make the separation any surface on the sector?
That when you click on any sector, he stood out.
At least for the terrain.

2

somebody tell me

3

nobody no help?

4

People would help if you done 2 things

  1. Explain as much as possible as to what problem you are having.

  2. DO NOT say somebody tell me.

If you do this then i am sure people will help you as this community is amazing.