Using VBA To Select A Row And Colour Code It Based On Conditions

I've had a look through the forum and can't see an answer, so apologies if I'm duplicating something!

I have a spreadsheet where column O has five conditions:
1 PO in
2 High Probability
3 Medium Probability
4 Low Probability
Blank

I need to colour code the whole row based on the value in the cells; if there were four conditions, I could do this with conditional formatting, but with five (with white as the fifth condition), I need to look at VBA.

However, I'm having difficulty colouring the whole row; how do I do this?

e.g. what I need to do is:
If O2 = "1 PO in"; Select A2:T2; Colour green

In addition, I need to ensure that if there is no data in column D, but column O is "1 PO in", it is highlighted in a separate colour. I have a macro for that, but don't know whether in needs to be put into the code before or after the macro needed above...