C#与ArcGis Engine的极其基础的问题 忘高人指教 谢谢

namespace _dnMap1
{
public partial class Form1 : Form
{
private ESRI.ArcGIS.Controls.IMapControl3 m_mapControl = null;
private ESRI.ArcGIS.Controls.IPageLayoutControl2 m_pageLayoutControl = null;
private IMapDocument pMapDocument;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
m_mapControl = (IMapControl3)this.axMapControl1.Object;
m_pageLayoutControl = (IPageLayoutControl2)this.axPageLayoutControl1.Object;
}
private void New_Click(object sender, EventArgs e)
{
}
private void AddData_Click(object sender, EventArgs e)
{
int currentLayerCount = this.axMapControl1.LayerCount;
ICommand pCommand = new ControlsAddDataCommandClass();