Cell colours for negative and positive values

[Kuler]

First of all I'm a real Excel novice so please bear that in mind!

I've got 12 months worth of business accounts which have been downloaded onto a single spreadsheet.
These show negative and positive values. As I only want to work on the negative figs at the moment, how do I highlight the colour of the positive value cells or font to prevent any mistakes ?

Thanks for any advice.

Kuler

[Izandol]

You may select the number cells then press Ctrl+1 and choose the Number format to give negative numbers red font?