Help with cast-ons for charts!

When you knit from a chart that uses two colors, do you cast on with one of them or both? because my chart and directions dont specify! hmm… this is my first chart-knitting experience and i dont want it to go bad! please any help would be very much appreciated! :muah: :muah:

You cast on with one color, and introduce the contrasting color when it appears in the chart.