You should add each row of your matrix as an additional series. Here is my code from an application I wrote a while back:
chart.ChartAreas.Add(new System.Windows.Forms.DataVisualization.Charting.ChartArea("BidAsk"));
chart.Series.Add(new System.Windows.Forms.DataVisualization.Charting.Series("Bid"));
chart.Series.Add(new System.Windows.Forms.DataVisualization.Charting.Series("Ask"));
chart.Series["Bid"].ChartType = SeriesChartType.StepLine;
chart.Series["Bid"].Points.DataBindXY(dView, "Timestamp", dView, "BidPrice");
chart.Series["Bid"].ChartArea = "BidAsk";
chart.Series["Ask"].ChartType = SeriesChartType.StepLine;
chart.Series["Ask"].Points.DataBindXY(dView, "Timestamp", dView, "AskPrice");
chart.Series["Ask"].ChartArea = "BidAsk";
The DataBindXY line is where you will set the values for Y. You will probably just use DataBindY.