Drag and drop ProgressBar Control and a button from toolbox on the window Form.

By default maximum value of ProgressBar is set 100 and minimum value is set 0 you can change this value.

Code:

Write code on button click event.

Double click on Click event.

private void button1_Click_1(object sender, EventArgs e)
{
            while (progressBar1.Value < 100)
                progressBar1.Value += 5;
}

Run the project

When you click show button then Progress Bar will start.