How to Open Telerik Rad Pop up Window Asynchronously?

Here I have a good example. See here for demo.

aspx file:

<telerik:RadScriptManager id="ScriptManager1" runat="server" />

 <telerik:RadAjaxManager ID="RadAjaxManager1" runat="server" OnAjaxRequest="RadAjaxManager1_AjaxRequest"/>
 <p>
   Press the submit button in order to start monitoring custom progress
 </p>
 <asp:button ID="buttonSubmit" runat="server" Text="Submit" OnClick="buttonSubmit_Click" CssClass="RadUploadButton" />

 <telerik:RadProgressManager id="Radprogressmanager1" runat="server" />

 <telerik:RadProgressArea id="RadProgressArea1" runat="server" />

aspx.cs file:

    protected void Page_Load(object sender, System.EventArgs e)
    {
        if (!IsPostBack)
        {
            //Do not display SelectedFilesCount progress indicator.
            RadProgressArea1.ProgressIndicators &= ~ProgressIndicators.SelectedFilesCount;
        }

        RadProgressArea1.Localization.Uploaded = "Total Progress";
        RadProgressArea1.Localization.UploadedFiles = "Progress";
        RadProgressArea1.Localization.CurrentFileName = "Custom progress in action: ";
    }

    protected void buttonSubmit_Click(object sender, System.EventArgs e)
    {
        UpdateProgressContext();
    }

    private void UpdateProgressContext()
    {
        const int total = 100;

        RadProgressContext progress = RadProgressContext.Current;
        progress.Speed = "N/A";

        for (int i = 0; i < total; i++)
        {
            progress.PrimaryTotal = 1;
            progress.PrimaryValue = 1;
            progress.PrimaryPercent = 100;

            progress.SecondaryTotal = total;
            progress.SecondaryValue = i;
            progress.SecondaryPercent = i;

            progress.CurrentOperationText = "Step " + i.ToString();

            if (!Response.IsClientConnected)
            {
                //Cancel button was clicked or the browser was closed, so stop processing
                break;
            }

            progress.TimeEstimated = (total - i) * 100;
            //Stall the current thread for 0.1 seconds
            System.Threading.Thread.Sleep(100);
        }
    }    

Now it should be easier to integrate your code.

EDIT: To trigger your Database operation after setting up your RadProgressArea in the PageLoad, you'll need some ajax call to be made after first page load (So I just added the RadAjaxManager to the ascx file upper). Use this code to trigger your DataBase call:

javascript:

 function pageLoad(sender, eventArgs) {
     if (!eventArgs.get_isPartialLoad()) {
         $find("<%= RadAjaxManager1.ClientID %>").ajaxRequest("StartDBOperation");
     }
 }    

ascx.cs file:

    protected void RadAjaxManager1_AjaxRequest(object sender, Telerik.Web.UI.AjaxRequestEventArgs e)
    {
        if (e.Argument == "StartDBOperation")
        {
            // Start DB operation here..
        }
    }