The cell and text colour dialogs look the same, and can be found on the Home
tab, and the Font group.

Another way of saying what Bob said:

First, highlight the cells you want to be a different color. Now, at the top
(usually right), where all of the toolbars are, you should see a paintbucket
with some color beneath it, next to a letter A with a line of color beneath
it. If you can't see this, go to View>Toolbars>and check Formatting.

Once you have located the paintbucket, click the little drop down arrow just
to the right of it and select the color you want. Now you're done!

You can change the font color in the selected cells the same way by using
the A icon.