image upload

html
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
    <script type="text/javascript">
        function showFileSelector() {
            var fileControl = document.getElementById("fileLogo");
            fileControl.click();
            return false;
        }

        function getFileAndPath() {

            var fileControl = document.getElementById("fileLogo");

            var lblUploadedLogo = document.getElementById("lblUploadedLogo");
            lblUploadedLogo.innerHTML = fileControl.value;

            $("#manageFile").show();
        }
    </script>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
    <table width="100%" cellpadding="10px" cellspacing="0">
        <tr>

                       
                       
                        <td  valign="top">
                            <div style="width: 76px; height: 78px; background-color: #F2F2F2; border: 1px solid #CFCFCF;
                                padding: 10px;">
                                <asp:Image ID="imgLogo" ImageUrl="~/images/Default_Image.jpg" ToolTip="Click to upload / change Image."
                                    runat="server" Width="76px" Height="78px" onclick="return showFileSelector()"
                                    Style="cursor: pointer" />
                                <asp:FileUpload ClientIDMode="Static" ID="fileLogo" runat="server" onchange="getFileAndPath();"
                                    Style="display: none;" />
                                <asp:HiddenField ID="hdnLogoPath" runat="server" />
                                <asp:HiddenField ID="hdnUploadedLogo" runat="server" />
                            </div>
                            <div id="manageFile" style="display: none; float: left">
                                <asp:Label ID="lblUploadedLogo" ClientIDMode="Static" runat="server" Text="Label"></asp:Label>
                                <asp:LinkButton ID="lnkUploadLogo" runat="server" OnClick="lnkUploadLogo_Click">Upload</asp:LinkButton>
                            </div>
                        </td>
                    </tr>
    </table>
</asp:Content>


//////////
c#:
protected void lnkUploadLogo_Click(object sender, EventArgs e)
    {
        string fileName = DateTime.Now.ToString("yyyyMMddhhmmss") + "_" + Path.GetFileName(fileLogo.PostedFile.FileName);

        fileLogo.PostedFile.SaveAs(Server.MapPath(@"TempFiles/" + fileName));//TempFiles is folder , you have to create its for temporary period.

        imgLogo.ImageUrl = @"TempFiles/" + fileName;
        hdnUploadedLogo.Value = @"TempFiles/" + fileName;
    }

//upload image to a permanent folder at the time of save.
private string UploadImage(string countryId)
    {
        string galleryPath = string.Empty;
        string mappedPath = string.Empty;

        if (hdnUploadedLogo.Value != "")
        {
            FileInfo tempfile = new FileInfo(Server.MapPath(hdnUploadedLogo.Value));
            mappedPath = Server.MapPath(@"../Repository/ImageGallery") + @"\" + countryId;

            if (!Directory.Exists(mappedPath))
                Directory.CreateDirectory(mappedPath);

            if (Directory.Exists(mappedPath + @"\" + tempfile.Name))
            {
                FileInfo oldfile = new FileInfo(mappedPath + @"\" + tempfile.Name);
                oldfile.Delete();
            }

            tempfile.MoveTo(mappedPath + @"\" + tempfile.Name);

            galleryPath += "../Repository/ImageGallery/" + countryId + "/" + tempfile.Name;
        }
        else
            galleryPath = hdnLogoPath.Value;

        return galleryPath;
    }








in case of thumbnail one ex is
 ImagePath = "";
        ThumbnailPath = "";

        string imageMappedPath = "";
        string thumbnailMappedPath = "";

        if (hdnUploadedContent.Value != "")
        {
            FileInfo tempfile = new FileInfo(Server.MapPath(hdnUploadedContent.Value));
            imageMappedPath = Server.MapPath("../Repository/EventGallery/") + Id + "/Images/";
            thumbnailMappedPath = Server.MapPath("../Repository/EventGallery/") + Id + "/Thumbnails/";

            if (!Directory.Exists(imageMappedPath))
                Directory.CreateDirectory(imageMappedPath);

            if (!Directory.Exists(thumbnailMappedPath))
                Directory.CreateDirectory(thumbnailMappedPath);

            System.Drawing.Image uploadedImage = System.Drawing.Image.FromFile(Server.MapPath(hdnUploadedContent.Value));
            System.Drawing.Image image = GlobalOperations.ResizeImage(uploadedImage, new System.Drawing.Size(400, 300));
            System.Drawing.Image thumbnail = GlobalOperations.ResizeImage(uploadedImage, new System.Drawing.Size(100, 100));

            image.Save(imageMappedPath + tempfile.Name);
            thumbnail.Save(thumbnailMappedPath + tempfile.Name);

            ImagePath += "~/Repository/EventGallery/" + Id + "/Images/" + tempfile.Name;
            ThumbnailPath += "~/Repository/EventGallery/" + Id + "/Thumbnails/" + tempfile.Name;

            uploadedImage.Dispose();
            File.Delete(Server.MapPath(hdnUploadedContent.Value));
        }
        else
        {
            ImagePath = hdnContentImagePath.Value.ToString();
            ThumbnailPath = hdnThumbnailPath.Value.ToString();
        }