string rgb = "#FFFFFF";
int r = Convert.ToInt16( "0x" + rgb.Substring(1,2), 16);
int g = Convert.ToInt16("0x" + rgb.Substring(3, 2), 16);
int b = Convert.ToInt16("0x" + rgb.Substring(5, 2), 16);
System.Drawing.Color color = System.Drawing.Color.FromArgb(r, g, b);