How do I change font colour in an if command?

E.g

IF(A1=10, "OK", "NOT OK"{I want to display this text in another colour to
stand out})

You would have to do this with Conditional Formatting (from the Format
menu). Select the cell then Format | Conditional Formatting and in the
panel Cell Contents type "NOT OK" then click the Format button and
choose your font/colour/effect and background colour (patterns tab),
then OK your way out.

Hope this helps.

Pete