How to show different parts in the plot in RooFit, just like TLegned in Root

i use a gauss plus 2nd chebychev to fit data in roofit. i want to show the red line is gauss, blue line is 2nd chebychev, and black line is data in the plot, just like TLegend in root. how should do that? Thanks

May be gPad->BuildLegend()

Thanks, i will try it.