Open page in new tab using C#

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C#

Javascript

Hi. Can someone help me with codes that can open a new page on button click event.
However, the twist is that a function has to be executed first before redirecting to a different page and the current page to reload.

Here is what I tried:

Page Name: ~/Application/BenefitsRequest.aspx

<asp:Button ID="btnSubmit" runat="server" Text="Submit & Print" Width="150px" OnClick="btnSubmit_Click" OnClientClick="if(confirm('Do you want to submit and print the reimbursement?')){this.style.background='#98201a url(../Images/HeaderFooterMainTemplate/loader.gif)'; this.value = 'Processing...';}else{return false;}" />

protected void btnSubmit_Click(object sender, EventArgs e)
{
   string toDate="";
   string fromDate="";
   fromDate = "1/1/1900";
   toDate = "1/1/1900";
        
   try
   {
      Label lblLoggedAs = (Label)Master.FindControl("lblLoggedAs");
      AddReimbursement("3", drpReimburseType.SelectedValue.ToString());//THIS IS A FUNCTION
      DeleteAllTrxRecord(); //THIS IS A FUNCTION
      string url = "~/Printing/ReimbursePrint.aspx?pg=3";
      Page.ClientScript.RegisterStartupScript(this.GetType(), "openlink", "window.open(url);", true);  
      Response.Redirect("~/Application/BenefitsRequest.aspx");
    }
    catch (Exception ex)
    {
      ClientScript.RegisterStartupScript(typeof(Page), "Error", "<script type='text/javascript'>alert('"+ex.Message+"')</script>");
     }
}

What I have tried:

i TRIED THE ABOVE CODE, please comment if u have questions