Conditional Formating - If cell = another cell green if ok or red if not ok

Totally not sure how to doe this. Have searched the web and this forum specifically on CF.

Currently I have In Cell F40... =IF(F37:F39=F10,"ok","not ok")
All cells 'should' be formated to currency.

F10 is cost of widget
F37 through F39 is new cost of widget +fees +donations, etc.
F40 is total of 37:39.
I am simply trying to ensure that the two cells equal.

I would like to add the color to the above once the above is working.

Thanks much
Mac

Select the range to format and go to Format|Conditional Formatting... choose Cell Value is >> Equal to >> and enter: ="ok"

click Format and choose the colour from Pattern tab.

Click OK.. click Add and then repeat for "not ok"