Change cell color based on other cell value

Hi ,

I have data updating in range "H30 to H186". If any value is going more than 2 in C column cell color to be change in yellow.

For example H40 value is >= +or- 2 then C40 cell color to be change in yellow and popup message to be display that " C40 value is crossed 2"

Can any one help me how to write the code for this