Sheet Class

public sealed class Sheet : LTComponent, 
	IWin32Window, IDocumentProperty, IDynamicMetaObjectProvider

Public NotInheritable Class Sheet
	Inherits LTComponent
	Implements IWin32Window, IDocumentProperty, IDynamicMetaObjectProvider

public partial class Form1 : Form
{
    public Form1()
    {
       InitializeComponent();

       //Add EventHandler
       emControl.Events.DocumentChanged += new Easymap._IECtlEvents_DocumentChangedEventHandler(Events_DocumentChanged);

       //Begin loading the workbook
       emControl.BeginLoadFromFile("Path of workbook");
    }

   //DocumentChanged Event, gets fired when document loaded
   private void Events_DocumentChanged(object sender, EventArgs e)
   {
        if (emControl.Document != null)
        {
            var layerForSelectionContainer = emControl.Document.CurrentSheet.Items.FindByCaption("Postalcode - Areas");
            if (layerForSelectionContainer != null)
            {
                //Set the specified layer for selecting elements.
                emControl.Document.CurrentSheet.SelectionContainer = (Easymap.IWindowlessComponent)layerForSelectionContainer;

                //Lock the selection container. Only elements in this layer can be selected.
                emControl.Document.CurrentSheet.LockSelectionContainer = true;
            }

            //Add SelectionChangedEventHandler, to act when the user select elements in EasyMapControl
            emControl.Document.CurrentSheet.SelectionChanged += new Easymap.SheetEvents_SelectionChangedEventHandler(CurrentSheet_SelectionChanged);
        }
    }

    //Occures when SelectionChangedEventHandler was fired
    private void CurrentSheet_SelectionChanged(object sender, EventArgs args)
    {
        //Do something if Count > 0
        if (emControl.Document.CurrentSheet.SelectedObjects.Count == 0)
            return;

        //Foreach IWindowlessComponent in the collection must be casted to LayerElementComponent to get the area id.
        for (int i = 0; i < emControl.Document.CurrentSheet.SelectedObjects.Count; i++)
        {
            Easymap.IWindowlessComponent obj = emControl.Document.CurrentSheet.SelectedObjects.get_Item(i);

            if (obj is Easymap.LayerElementComponent)
            {
                var layerElementComponent = (Easymap.LayerElementComponent)obj;
                string areaID = layerElementComponent.LayerElement.Key;
            }
        }

    }
}