We will first create a marbled pattern and then use the fill tool to place the image on the text.
You can also create different colors by adding a new layer underneath the marbled pattern and using the layer transparency slider bar to change the transparency of the top layer.
Below are examples of using different bottom layer colors to create different colored marble.
To do this create a new layer and flood fill it with a solid color. Move the new layer UNDER
the marble layer by clicking and dragging it underneath in the layer palette
You can also use the colors/colorize tool to create a different color.