Drawing a Line Chart

/*
A single data set should be contained in an int[] or a float[]
Use -1 for missing values
*/
int [] data = new int[] { 40, 30, 20, 10, 0 };

// Specify chart width and height in pixels
LineChart chart = new LineChart(150, 150);

// SetData will accept int[] and float[] for single data sets
chart.SetData(data);

string imageUrl = chart.GetUrl();

Adding Axes

int [] data = new int[] { 40, 30, 20, 10, 0 };

LineChart chart = new LineChart(150, 150);
chart.SetData(data);

/*
Create an axis along the bottom of the graph
Labels will be automatically generated by the API using the range values.
*/
ChartAxis bottomAxis = new ChartAxis(ChartAxisType.Bottom);
bottomAxis.SetRange(0, 500);
bottomAxis.HexColor = "00FF00";
bottomAxis.FontSize = 14;
chart.AddAxis(bottomAxis);

/* 
Create an axis along the top of the graph
This time we specify the labels ("text", position)
The default range for an axis is 0-100
*/
ChartAxis topAxis = new ChartAxis(ChartAxisType.Top);
topAxis.AddLabel(new ChartAxisLabel("one", 0));
topAxis.AddLabel(new ChartAxisLabel("two", 75));
topAxis.AddLabel(new ChartAxisLabel("three", 100));
chart.AddAxis(topAxis);

string imageUrl = chart.GetUrl();

Working with multiple data sets

/*
Each data set should be contained in an int[] or float[]
To work the multiple data sets add them to a data structure that implements ICollection
*/
float[] set1x= new float[] { 0, 30, 60, 70, 90, 95, 100 };
float[] set1y = new float[] { 20, 30, 40, 50, 60, 70, 80 };
float[] set2x = new float[] { 10, 30, 40, 45, 52 };
float[] set2y = new float[] { 100, 90, 40, 20, 10 };

List<float[]> dataList = new List<float[]>();
dataList.Add(set1x);
dataList.Add(set1y);
dataList.Add(set2x);
dataList.Add(set2y);

LineChart lineChart = new LineChart(150, 150, LineChartType.MultiDataSet);
lineChart.SetData(dataList);

// Optional : Provide a hex color for each pair of data sets
lineChart.SetDatasetColors(new string[] { "FF0000", "00FF00" });

// Optional : Provide a label for each pair of data sets
lineChart.SetLegend(new string[] {"First", "Second"});

string url = lineChart.GetUrl();

XKCD Example

// These data represent the Y-axis coordinates of the line
// They will be evenly spaced along the X-axis
float[] data = new float[] {35, 30, 26, 22, 17,  5, 96,  5,  4,  3,  2,  2,  1,  1};

// Create the bottom X-axis that will contain the BAC numbers
ChartAxis bottomAxis = new ChartAxis(ChartAxisType.Bottom);
bottomAxis.SetRange(0, 30);

string[] axisLabels = new string[] {".00", ".02", ".04", ".06", ".08", ".10",
                                    ".12", ".14", ".16", ".18", ".20", ".22",
                                    ".24", ".26"};

// The labels are positioned across the X-axis in relation to the axis range
// They will be located at positions {0, 2, 4, 6 ... 28}
for (int i = 0; i < axisLabels.Length; i++)
{
    bottomAxis.AddLabel(new ChartAxisLabel(axisLabels[i], i*2));
}

// Create another bottom X-axis that we will stack under our BAC numbers
ChartAxis bottomAxis2 = new ChartAxis(ChartAxisType.Bottom);
bottomAxis2.AddLabel(new ChartAxisLabel("Blood Alcohol Concentration (%)", 50));

LineChart lineChart = new LineChart(400, 200);
lineChart.SetTitle("Programming Skill", "000000", 14);
lineChart.SetData(data);

// If two axis are set to the same location the first one added will be closest
// to the chart
lineChart.AddAxis(bottomAxis);
lineChart.AddAxis(bottomAxis2);
return lineChart.GetUrl();

See this chart