[C#] Progress Bars with SHA1CryptoServiceProvider help!

I am trying to report progress of the SHA1CryptoServiceProvider which is getting the SHA1 hash of an input file to the progress bar. I have the SHA1CryptoServiceProvider in one background process and a timer in another. The timer is what is reporting progress as I don't know how to do it with the SHA1CryptoServiceProvider. The problem is that I need to either get the SHA1CryptoServiceProvider to report progress or have according to the file size the program guess how long it will take and increment the progress bar correctly. Both so that the progress bar is at 100 or very close when the hash is completed.
Here is my code.

View attachment WindowsFormsApplication1.rar

Code:

 string strfilepath;
        string hash;
        long s1;
        float s2;
        FileInfo f;
        bool running;
        private void btnBrowse_Click(object sender, EventArgs e)
        {
            openFD.InitialDirectory = "C:/";
            openFD.Title = "Please Select An ISO";
            openFD.FileName = "";
            openFD.Filter = "ISO Files|*.iso";

            if (openFD.ShowDialog() != DialogResult.Cancel)
            {
                txtFilepath.Text = openFD.FileName;
            }
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            try
            {
                strfilepath = txtFilepath.Text;
                f = new FileInfo(strfilepath);
                s1 = f.Length;
                MessageBox.Show(Convert.ToString(s1));
                s2 = s1 / 102400000;
                s2 = s2 / 100;
                s2 = s2 / 1.4F;
                MessageBox.Show(Convert.ToString(s2));
                if (File.Exists(strfilepath))
                {
                    if (bw.IsBusy != true)
                    {
                        running = true;
                        bw.RunWorkerAsync();
                    }
                    if (bw2.IsBusy != true)
                    {
                        bw2.RunWorkerAsync();
                    }
                    if (running == true)
                    {
                        MessageBox.Show("Running");
                        running = false;
                    }
                }
            }
            catch (System.Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message, "Error!",
                         System.Windows.Forms.MessageBoxButtons.OK,
                         System.Windows.Forms.MessageBoxIcon.Error,
                         System.Windows.Forms.MessageBoxDefaultButton.Button1);
            }
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            hash = GetSHA1Hash(strfilepath);
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {

        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if ((e.Cancelled == true))
            {
                MessageBox.Show("Canceled!");
            }

            else if (!(e.Error == null))
            {
                MessageBox.Show("Error: " + e.Error.Message);
            }

            else
            {
                    bw2.CancelAsync();
                    MessageBox.Show("Hash Made!");
                    txtHash.Text = hash;
            }
        }

        public static string GetSHA1Hash(string filename)
        {
            string strHash = "";

            StreamReader sr = new StreamReader(filename);
            SHA1CryptoServiceProvider sha1h = new SHA1CryptoServiceProvider();

            try
            {
                strHash = BitConverter.ToString(sha1h.ComputeHash(sr.BaseStream));
                sr.Close();
                strHash = strHash.Replace("-", "");
            }
            catch (System.Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message, "Error!",
                         System.Windows.Forms.MessageBoxButtons.OK,
                         System.Windows.Forms.MessageBoxIcon.Error,
                         System.Windows.Forms.MessageBoxDefaultButton.Button1);
            }

            return strHash;
        }

        private void bw2_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 1; i <= 100; i++)
            {
                if ((bw2.CancellationPending == true))
                {
                    e.Cancel = true;
                    break;
                }
                else
                {
                    Thread.Sleep(446);
                    bw2.ReportProgress(i);
                }
            }
        }

        private void bw2_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
            this.Text = e.ProgressPercentage.ToString() + "%";
        }

        private void bw2_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if ((e.Cancelled == true))
            {
                MessageBox.Show("Timer Stopped!");
            }

            else if (!(e.Error == null))
            {
                MessageBox.Show("Error: " + e.Error.Message);
            }

            else
            {
                MessageBox.Show("Timer Done!");
                progressBar1.Value = 100;
            }
        }

 

Code:

f = new FileInfo(strfilepath);
                s1 = f.Length;
                MessageBox.Show(Convert.ToString(s1));
                s2 = s1 / 102400000;
                s2 = s2 / 100;
                s2 = s2 / 1.4F;
                MessageBox.Show(Convert.ToString(s2));

This part if the code was my attempt at getting the file size.
The first line successfully retrieves the file size but I don't know what to do with it after I have retrieved it.