Pop up

I have a spreadsheet linked to a database that automatically refreshes upon opening it. Is there way to create a pop-up window to give a warning when the value of a particular cell reaches a certain point?

To be more precise, when D2 reaches 500, I want a pop up window to say "You need to order Almond" & when D3 reaches 3800, I want a pop up windows to say "You need to order BARRIERCOAT".

I have others but I think help on that might clue me in on how to do the others.

Thanks.