You need to add some data to display, you add this to the Models Series property.
Line (X,Y) graph example.
public Graph()
{
InitializeComponent();
Plot = new OxyPlot.WindowsForms.Plot();
Plot.Model = new PlotModel();
Plot.Dock = DockStyle.Fill;
this.Controls.Add(Plot);
Plot.Model.PlotType = PlotType.XY;
Plot.Model.Background = OxyColor.FromRGB(255, 255, 255);
Plot.Model.TextColor = OxyColor.FromRGB(0, 0, 0);
// Create Line series
var s1 = new LineSeries { Title = "LineSeries", StrokeThickness = 1 };
s1.Points.Add(new DataPoint(2,7));
s1.Points.Add(new DataPoint(7, 9));
s1.Points.Add(new DataPoint(9, 4));
// add Series and Axis to plot model
Plot.Model.Series.Add(s1);
Plot.Model.Axes.Add(new LinearAxis(AxisPosition.Bottom, 0.0, 10.0));
Plot.Model.Axes.Add(new LinearAxis(AxisPosition.Left, 0.0, 10.0));
}
This Example: