How to call bootstrap modalpopup in usercontrol ?

Consider This being your Modal with some controls being inside of it:

<div id="modal" modal-content">
                <div class="modal-header">
                    <button type="button" class="close" data-dismiss="modal">×
                    </button>
                    <h4 class="modal-title">Register Form</h4>
                </div>
                <div class="modal-body">
                    <asp:Label runat="server"  Text="Enter  UserName"></asp:Label>
                    <asp:TextBox runat="server" class="form-control" ID="txtUserReg">
                    </asp:TextBox>
                    <br />
                    <br />
                 
                    <asp:TextBox runat="server" TextMode="Password" ID="txtPassReg">
                    </asp:TextBox>
                </div>
                <div class="modal-footer">
                    <asp:Button  ID="btnSave" Text="Save" OnClick="Register_Click" 
                     runat="server" />
                </div>
</div>

You have to Create a button or a control that on click you will Show your modal or on some sort of event..
If you want to make the modal pop up the you have to use some javascript:

   <pre><script>
    $(document).ready(function () {
        $("#Button1").click(function () {
            $("#modal").show(300);
            $(".showHideModal").show();
        });

        $(".showHideModal").click(function () {
            $("#modal").hide(300);
            $(".showHideModal").hide();
        });
    });
</script>

I Hope this will help you Out!!