How to plot time-series overlayed on the same graph with differen t colors

Hello Visad Community:
I am new to visAD. I have a question about display time-series. I have
time-series data, y(i)=f(x(i))+iK (i=1,...N, K=const). I want to plot them
on the same graph with different colors to distinguish the lines. How can it
be implemented?
Thanks
Xiaodong