// Create an extension page from a specified page type
ExtensionPageData page = ExtensionPageData.Create(PageReference.StartPage, pageTypeID);
// Get the collection of available content area on the extension page
IList<ContentAreaData> areas = page.GetContentAreas();

ContentFunctionData imageFunction = ContentFunctionData.Create(extensionPageLink, imageFunctionType);

// load extension page collection
PageTypeCollection pageTypes = Dropit.Extension.Global.ListExtensionPageTypes();

// load content function
IList<ContentFunctionType> functionTypes = Dropit.Extension.Global.ListContentFunctionTypes();

// create an extension page            
ExtensionPageData page = ExtensionPageData.Create(PageReference.StartPage, pageTypes[0].ID);
page.CurrentPage.PageName = "Test Page " + DateTime.Now;

// create 1st content function: BLOCK
ContentFunctionData block = ContentFunctionData.Create(page.CurrentPage.PageLink, functionTypes[0].FunctionTypeID);
// get the left content area from the page
ContentAreaData contentArea = page.GetContentAreas()[0];
// insert to the left content area at 0
contentArea.InsertContentFunction(block, 0);

// create 2nd content function: TEXT
ContentFunctionData text = ContentFunctionData.Create(page.CurrentPage.PageLink, functionTypes[1].FunctionTypeID);
// get the right content area from the page
contentArea = page.GetContentAreas()[1];
// insert to the right content area at 0
contentArea.InsertContentFunction(text, 0);

// create 3rd content function: IMAGE
ContentFunctionData image = ContentFunctionData.Create(page.CurrentPage.PageLink, functionTypes[2].FunctionTypeID);
// get the left content area of content function BLOCK
contentArea = block.GetContentAreas()[0];
// insert to the left content area at 0
contentArea.InsertContentFunction(image, 0);

PageReference pageLink = page.Save(EPiServer.DataAccess.SaveAction.Publish, EPiServer.Security.AccessLevel.NoAccess);

 public partial class ExtensionDemoPage : TemplatePage
 {
    // ExtensionPageHandler for Extension Functionality
    ExtensionPageHandler extensionPageHandler;

    public ExtensionDemoPage():base(0,0)
    {
        // create an instance of ExtensionPageHandler
        extensionPageHandler = new ExtensionPageHandler();
    }

    protected override void OnInit(System.EventArgs e)
    {
        base.OnInit(e);
        // initialize ExtensionPageHandler instance
        // must always be placed at this position
        extensionPageHandler.Initialize(this);
    }
}