You can change the font color to whatever you like.  You must be new to MS
Office (not just PowerPoint) to ask a question like that.

Just make a text box, right click, Format Text Box, and choose Color.  It
will reveal a color pallette that you can choose any color from.  If you
already have specific colors in mind, it would be worth finding out what the
color code is in RBG.. and then you can just type that into the color palette
and get the exact same color you want.

Hi Esther & welcome, dont worry even experts at powerpoint would have
problems getting a good metallic fill for text!

As above you can fill text with any solid colour, however no single colour
will look convincingly metallic. Best bet in powerpoint is to use word art
and in format > word art > colour go to fill effects and look at the preset
gradients where you will find gold, copper etc.

To be honest none of these is really that convincing but to do betteryou
will have to use a program like photoshop

Esther,
Colors such as Gold, Silver, Copper, Bronze are denoted by hex, RGB, CMYK or
HSV value. If you know the correct value, you will be able to get the color
you want, for the exception that you will only be getting them in plain
colors. To further enhance them, you can try out Fill Effects which has been
mentioned above.

Here's a list of colors and the values at Wikipedia:
http://en.wikipedia.org/wiki/List_of_colors

Look for the colors names you want from Wikipedia, and check their RGB
values. Then, follow the steps Dawgma has given.