1.In Web.config file in handlers section 2.Add Captcha DLL to AddReferences 3.Aspx cc1:CaptchaControl ID="CaptchaControl1" runat="server" asp:Label ID="lbltext" Text="enter the above code here:" runat="server asp:TextBox ID="txtCaptch" runat="server" asp:Label ID="lblmessage" runat="server" 4.in button click write(Aspx.cs) if (!CaptchaControl1.UserValidated) { lblmessage.Text = "You Enterted Text Doesn't Match"; return; } else { lblmessage.Text = "Secuessfully entered"; CaptchaControl1.Visible = false; txtCaptch.Visible = false; lbltext.Visible = false; lblmessage.Visible = false; }