Hello wmswat,
What you need to do is highlight the column that the data will be in. From there you can click the Conditional Formatting drop-down icon on the Home tab. Click New Rule.
The Rule type you will want to utilize "Format Only Cells That Contain". From there you can tell it to Format Only Cells With: Specific Text containing "PN" (for example) with the Format color of green.
Once you do that you can just add a different Conditional Formatting for each of the other cells you wont too.
Let me know if this helps!