hi

how to catch data without refreshing page

I use the below codes in page:

<div id="captchaE" class="attenCC1M" runat="server" visible="false">
    <asp:Label ID="Label24" runat="server" CssClass="lblattenCC1M">خطا:&nbsp&nbsp<span style="font:13px Mj_Dinar Two Light;color:#c6b85e">پاسخ سوال امنیتی اشتباه می باشد.</span></asp:Label>
    <asp:Image ID="Image7" runat="server" CssClass="imgattenMD1" ImageUrl="~/Image/main/attenm.png"></asp:Image>
</div>

here <div id=captchaE visible="false"> and in else condition that will be true:

else
{
    captchaE.Visible = true;
    DsendC.Visible = false;
    ClientScript.RegisterStartupScript(this.GetType(), "Popup", "$('#myModal2').modal('show')", true);
}

when I click the button it will refresh the page and do if or else conditions I want doesn't refresh the page and do if or else condition

protected void ImgsendMessage_Click(object sender, ImageClickEventArgs e)
{ 
    if (txtStopSpam.Text == ViewState["spam"].ToString()) 
    {        
        captchaE.Visible = false;
        DsendC.Visible = false;
        using (SqlConnection conn = General.GetConnection())
        {
            using (SqlCommand _cmd = General.GetCommand("MessageNew_insertInfo", conn))
            {
                conn.Open();
 
                _cmd.Parameters.AddWithValue("@Topic", Txttopic.Text);
                _cmd.Parameters.AddWithValue("@Name", Txtname.Text);
                _cmd.Parameters.AddWithValue("@Description", Txtdes.Text);
                _cmd.Parameters.AddWithValue("@Tell", Txtmobile.Text);
                _cmd.Parameters.AddWithValue("@email", "");
                _cmd.ExecuteNonQuery();
 
            }
        }     
        DsendC.Visible = true;
        ClientScript.RegisterStartupScript(this.GetType(), "Popup", "$('#myModal3').modal('show')", true);
        generateStopSpamText();
    }
 
    else
    { 
        captchaE.Visible = true;
        DsendC.Visible = false;
        ClientScript.RegisterStartupScript(this.GetType(), "Popup", "$('#myModal2').modal('show')", true); 
    } 
}

how I can do it?

Best regards

Neda