To Add Color Keys to a Gradient Fill

From the Active Color dialog, select the Gradient Fill tab.
From the Type option menu, select the fill type.
From the Color Mode option menu, select Multiple Colors.
Enter a data point on the color bar at the desired position for the key.
The key is added. Initially, the color is set to the interpolated value of the gradient at that point.
Repeat the above step for further color keys, as required. MicroStation allows a maximum of six intermediate color keys.