How to open the Select File Dialog and Select Directory Dialog

private void BrowseButton_Click(object sender, RoutedEventArgs e)
        {
            OpenFileDialog dialog = new OpenFileDialog();
            if((this)== true)
            {
                 = ;
            }
        }

private void DisplayButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                FolderBrowserDialog dialog = new FolderBrowserDialog();
                 = "Please select the file path";
                DialogResult result = ();
                if(result == )
                {
                    return;
                }
                string folderPath = ();
                DirectoryInfo theFolder = new DirectoryInfo(folderPath);
                if ()
                {
                    //operate                    return;
                }

        /// <summary>
        /// File selection universal dialog box        /// </summary>
        public class FilesSelectDialog
        {
            public OpenFileDialog fileDialog;
            //The path is opened by default            public string DirPath = "D:\\";
            public string FilePath;
            public string Title;
            public string Filter= "picture(*.jpg,*.jpge,*.bmp,*.png)|*.jpg;*.jpge;*.bmp;*.png| All files(*.*) |*.*";
            public FilesSelectDialog(string title)
            {
                Title = title;
                fileDialog = new OpenFileDialog();//Open the file dialog            }
            public bool Show()
            {
                 = DirPath;//Initialize the path                 = Filter;//Filter option settings, text files, all files.                 = 0;//The second filter string is currently used                 = true;//Restore the original directory when the dialog box is closed                 = Title;
                if (() == )
                {
                    //for (int i = 1; i <= ; i++)
                    //{
                    //    if (( - i, 1).Equals(@"\"))
                    //    {
                    // //Change the default path to the most recent open path                    //        Path = (0,  - i + 1);
                    //        return true;
                    //    }
                    //}
                    FilePath = ;
                    try
                    {
                        DirPath = (FilePath);//Change the default path to the most recent open path                    }
                    catch (Exception)
                    {
                        return false;
                    }
                    return true;
                }
                else
                {
                    return false;
                }
            }
        }
FilesSelectDialog selectDialog = new FilesSelectDialog("Please select the picture you want to convert");
        private void Btn_OpenImsge_Click(object sender, EventArgs e)
        {
            //FilesSelectDialog selectDialog = new FilesSelectDialog("Please select the picture to be converted");             = "picture(*.jpg,*.jpge,*.bmp,*.png)|*.jpg;*.jpge;*.bmp;*.png| All files(*.*) |*.*";
            if (()==true)
            {
                 = ;
                //();
                DisplayImage();
            }
        }