How to: Add a Legend Title
To display the legend title, set the TitleBase.Visible property of the LegendBase.Title to true and specify the Title.Text of the LegendBase.Title. To customize the appearance of the title, you can change, for example, the AlignedTitle.Alignment, AlignedTitle.WordWrap and AlignedTitle.MaxLineCount properties to align the title to the left and divide it into several lines.
using System.Drawing;
// Specify legend title's text.
chart.Legend.Title.Text = "Area of countries";
// Show legend title.
chart.Legend.Title.Visible = true;
// Configure legend title appearance.
chart.Legend.Title.Alignment = StringAlignment.Near;
chart.Legend.Title.MaxLineCount = 3;
chart.Legend.Title.WordWrap = true;